Introduction to Java Programming and Data Structures, 12th edition Y Daniel Liang Test Bank by Ace Test Banks

Introduction to Java Programming and Data Structures, 12th edition By Y Daniel Liang

Email: richard@qwconsultancy.com

Chapter 1 Introduction to Computers, Programs, and Java Section 1.2 What is a Computer? 1. is the physical aspect of the computer that can be seen. a. Hardware b. Software c. Operating system d. Application program Key:a See the first paragraph in Section 1.2. # Section 1.2.1 What is a Computer? 2. is the brain of a computer. a. Hardware b. CPU c. Memory d. Disk Key:b See the first paragraph in Section 1.2.1. # 3. The speed of the CPU may be measured in . a. megabytes b. gigabytes c. megahertz d. gigahertz Key:cd See the third paragraph in Section 1.2.1. 1 megahertz equals 1 million pulses per second and 1 gigahertz is 1000 megahertz. # Section 1.2.2 Bits and Bytes 4. Why do computers use zeros and ones? a. because combinations of zeros and ones can represent any numbers and characters. b. because digital devices have two stable states and it is natural to use one state for 0 and the other for 1. c. because binary numbers are simplest. d. because binary numbers are the bases upon which all other number systems are built. Key:b See the second paragraph in Section 1.2.2. # 5. One byte has bits. a. 4 b. 8 c. 12 d. 16 Key:b See the thrid paragraph in Section 1.2.2. # 5. One gigabyte is approximately bytes. a. 1 million b. 10 million c. 1 billion d. 1 trillion Key:c See the fifth paragraph in Section 1.2.2. ..

# Section 1.2.3 Memory 6. A program and its data must be moved into the computer's a. memory b. hard disk c. CPU d. CD-ROM Key:a See the first paragraph in Section 1.2.3.

before they can be executed by the CPU.

# Section 1.2.4 Storage Devices 6. A computer's is volatile; that is, any information stored in it is lost when the system's power is turned off. a. memory b. hard disk c. flash stick d. CD-ROM Key:a See the first paragraph in Section 1.2.4. # 6. Which of the following are storage devices? a. portable disk b. hard disk c. flash stick d. CD-ROM Key:abcd See the second paragraph in Section 1.2.4. # Section 1.2.5 Input and Output Devices 7. The specifies the number of pixels in horizontal and vertical dimensions of the display device. a. screen resolution b. pixel c. dot pitch d. monitor Key:a See the third last paragraph in Section 1.2.5. # Section 1.2.6 Communications Devices 7. is a device to connect a computer to a local area network (LAN). a. Regular modem b. DSL c. Cable modem d. NIC Key:d See the bullet items in Section 1.2.6. # Section 1.3 Program Languages 8. are instructions to the computer. a. Hardware b. Software c. Programs d. Keyboards Key:bc See the Key Point in Section 1.3. # ..

9. Computer can execute the code in a. machine language b. assembly language c. high-level language d. none of the above Key:a See the first paragraph in Section 1.3.1.

# 10. translates high-level language program into machine language program. a. An assembler b. A compiler c. CPU d. The operating system Key:b See the first paragraph after Table 1.1 in Section 1.3.3. # Section 1.4 Operating Systems 11. is an operating system. a. Java b. C++ c. Windows d. Visual Basic e. Ada Key:c See the first paragraph in Section 1.4. # 12. is a program that runs on a computer to manage and control a computer's activities. a. Operating system b. Java c. Modem d. Interpreter e. Compiler Key:a See the first paragraph in Section 1.4. # Section 1.5 Java, World Wide Web, and Beyond 14. Due to security reasons, Java cannot run from a Web browser in the new version of Java. a. applications b. applets c. servlets d. Micro Edition programs Key:b See the last paragraph in Section 1.5. # 15. a. Java b. C++ c. C d. C# e. Python

is not an object-oriented programming language.

Key:c See Table 1.1 in Section 1.3.1. # 16.

is interpreted. ..

a. Java b. C++ c. C d. Ada e. Pascal Key:a See the second paragraph in Section 1.5. # 17. a. Java b. C++ c. C d. Ada e. Pascal

is architecture-neutral.

Key:a See the second paragraph in Section 1.5. # Section 1.6 The Java Language Specification, API, JDK, and IDE 18. is a technical definition of the language that includes the syntax and semantics of the Java programming language. a. Java language specification b. Java API c. Java JDK d. Java IDE Key:a See the last paragraph in Section 1.6. # 19. contains predefined classes and interfaces for developing Java programs. a. Java language specification b. Java API c. Java JDK d. Java IDE Key:b See the last paragraph in Section 1.6. # 20. consists of a set of separate programs for developing and testing Java programs, each of which is invoked from a command line. a. Java language specification b. Java API c. Java JDK d. Java IDE Key:c See the last paragraph in Section 1.6. # 21.

provides an integrated development environment (IDE) for rapidly developing Java programs. Editing,

compiling, building, debugging, and online help are integrated in one graphical user interface. a. Java language specification b. Java API c. Java JDK d. Java IDE Key:d See the last paragraph in Section 1.6. # ..

Section 1.7 A Simple Java Program

22. The main method header is written as: a. public static void main(string[] args) b. public static void Main(String[] args) c. public static void main(String[] args) d. public static main(String[] args) e. public void main(String[] args) Key:c In A, string should be spelled String with S in uppercase. In B, Main should be spelled main in lowercase. In D, the keyword void is missing. in D, the keyword static is missing. C is correct. # 23. Which of the following statements is correct? a. Every line in a program must end with a semicolon. b. Every statement in a program must end with a semicolon. c. Every comment line must end with a semicolon. d. Every method must end with a semicolon. e. Every class must end with a semicolon. Key:b Only statements need to be end with a semicolon. # 24. Which of the following statements is correct to display Welcome to Java on the console? a. System.out.println('Welcome to Java'); b. System.out.println("Welcome to Java"); c. System.println('Welcome to Java'); d. System.out.println('Welcome to Java"); e. System.out.println("Welcome to Java'); Key:b In A, a string must be enclosed in double quotation marks. In C, a string must be enclosed in double quotation marks and also the .out is missing. In D, a string must be enclosed in double quotation marks on both sides. In E, a string must be enclosed in double quotation marks. B is correct. # Section 1.8 Creating, Compiling, and Executing a Java Program 25. The JDK command to just compile a class (not run) in the file Test.java is a. java Test b. java Test.java c. javac Test.java d. javac Test e. JAVAC Test.java Key:c In A, java is the command to run a program. In B, java is the command to run a program. In D, java is the command to run a program. In E, The command is case sensitive. C is correct. # 26. Which JDK command is correct to run a Java application in ByteCode.class? a. java ByteCode b. java ByteCode.class c. javac ByteCode.java d. javac ByteCode e. JAVAC ByteCode Key:a A is correct. In B, to compile, use only the class name, not including the extension. In C, javac is the command to compile a class, not to run a class. In D, javac is the command to compile a class, not to run a class. In E, the command is case sensitive and javac is the command to compile a class, not to run a class. # 27. Java compiler translates Java source code into a. Java bytecode ..

b. machine code c. assembly code d. another high-level language code Key:a Java bytecode is the end result of compiling a Java source file. Java bytecode is machine-indepedent and can be run on any platform. # 28. is a software that interprets Java bytecode. a. Java virtual machine b. Java compiler c. Java debugger d. Java API Key:a Java virtual machine is a software that runs Java bytecode. Java compiler compiles Java source code into Java bytecode. # 29. Suppose you define a Java class as follows, the source code should be stored in a file named

public class Test { } a. Test.class b. Test.doc c. Test.txt d. Test.java e. Any name with extension .java Key:d You have to name the class as ClassName.java. Here the class name is Test. # 30. The extension name of a Java bytecode file is a. .java b. .obj c. .class d. .exe Key:c .java is the Java source code file name and .class is the Java bytecode file name. # 31. The extension name of a Java source code file is a. .java b. .obj c. .class d. .exe Key:a .java is the Java source code file name and .class is the Java bytecode file name. # 32. Which of the following lines is not a Java comment? a. /** comments */ b. // comments c. -- comments d. /* comments */ e. ** comments ** Key:ce The text that begins with // in a line is known as a line comment and the text that is enclosed between /* and */ is known as a paragraph comment. ..

# 33. Which of the following are the reserved words? a. public b. static c. void d. class Key:abcd These are all reserved words with specific meaning to the compiler. # 34. Every statement in Java ends with . a. a semicolon (;) b. a comma (,) c. a period (.) d. an asterisk (*) Key:a You have to tell the compiler where a statement ends using a semicolon. # 35. A block is enclosed inside . a. parentheses b. braces c. brackets d. quotes Key:b A block is enclosed inside a pair of openning and closing braces. # Section 1.9 Programming Style and Documentation 36. Programming style is important, because . a. a program may not compile if it has a bad style b. good programming style can make a program run faster c. good programming style makes a program more readable d. good programming style helps reduce programming errors Key:cd Bad style is a readability issue. The code will still compile. Programming style is a readability issue and it does not effect the performance of the code. D and C are correct. # 37.

Analyze the following code.

I: public class Test { public static void main(String[] args) { System.out.println("Welcome to Java!"); } } II: public class Test { public static void main(String[] args) { System.out.println("Welcome to Java!"); } } a. Both I and II can compile and run and display Welcome to Java, but the code in II has a better style than I. b. Only the code in I can compile and run and display Welcome to Java. c. Only the code in II can compile and run and display Welcome to Java. d. Both I and II can compile and run and display Welcome to Java, but the code in I has a better style than II. Key:d Both I and II are the same except the format is different. Format is a readability issue only. ..

# 38. Which of the following code has the best style? I: public class Test { public static void main(String[] args) { System.out.println("Welcome to Java!"); } } II: public class Test { public static void main(String[] args) { System.out.println("Welcome to Java!"); } } III: public class Test { public static void main(String[] args) { System.out.println("Welcome to Java!"); } } IV: public class Test { public static void main(String[] args) { System.out.println("Welcome to Java!"); } } a. I b. II c. III d. IV Key:d All the code will run fine, but not formatted correctly. Only the code in IV is formatted correctly. # Section 1.10 Programming Errors 39. If a program compiles fine, but it produces incorrect result, then the program suffers . a. a compile error b. a runtime error c. a logic error Key:c If a program has a compile error, it will not run. When a program has a runtime error, it terminates abnormally. C is correct. # 40. If you forget to put a closing quotation mark on a string, what kind of error will be raised? a. a compile error b. a runtime error c. a logic error Key:a This is a syntax error, which will be detected by the compiler.

Chapter 2 Elementary Programming Section 2.2 Writing a Simple Program 1. is the code with natural language mixed with Java code. a. Java program b. A Java statement c. Pseudocode d. A flowchart diagram key:c See the second paragraph in this section. # 2.

What is the exact output of the following code?

double area = 3.5; System.out.print("area"); System.out.print(area); a. 3.53.5 b. 3.5 3.5 c. area3.5 d. area 3.5 Key:c The first print statement prints a string followed by the second print statement that prints a number. # Section 2.3 Reading Input from the Console 3. Suppose a Scanner object is created as follows, what method do you use to read a real number? Scanner input = new Scanner(System.in); a. input.nextDouble(); b. input.nextdouble(); c. input.double(); d. input.Double(); Key:a The correct method to read a real number is nextDouble(). # 4. The following code fragment reads in two numbers. What is the incorrect way to enter these two numbers? Scanner input = new Scanner(System.in); int i = input.nextInt(); double d = input.nextDouble(); a. Enter an integer, a space, a double value, and then the Enter key. b. Enter an integer, two spaces, a double value, and then the Enter key. c. Enter an integer, an Enter key, a double value, and then the Enter key. d. Enter a numeric value with a decimal point, a space, an integer, and then the Enter key. Key:d See Listing 2.3. # 5. If you enter 1 2 3, when you run this program, what will be the output? import java.util.Scanner; ..

public class Test1 { public static void main(String[] args) { Scanner input = new Scanner(System.in); System.out.print("Enter three numbers: "); double number1 = input.nextDouble(); double number2 = input.nextDouble(); double number3 = input.nextDouble(); // Compute average double average = (number1 + number2 + number3) / 3; // Display result System.out.println(average); } } a. 1.0 b. 2.0 c. 3.0 d. 4.0 Key:b (1.0 + 2.0 + 3.0) / 3 is 2.0 # Section 2.4 Identifiers 6. Every letter in a Java keyword is in lowercase? a. true b. false Key:a It is true that the keywords in Java are in lowercase. For example, public, static, int, double, and void are the keywords. # 7. Which of the following is a valid identifier? a. $343 b. class c. 9X d. 8+9 e. radius Key:ae class is a keyword, which cannot be used as an identifier. Identifiers cannot start with a number. # Section 2.5 Variables 8. Which of the following are correct names for variables according to Java naming conventions? a. radius b. Radius c. RADIUS d. findArea e. FindArea Key:ad A single-word variable is in lowercase. In a multiple-word variable, the words are concatenated with the first word in lowercase and the first letter of each subsequent word in uppercase. # 9. a. b.

Which of the following are correct ways to declare variables? int length; int width; int length, width; ..

c. int length; width; d. int length, int width; Key:ab Note that a semicolon ends a statement. In B, length and width are both declared as int. # Section 2.6 Assignment Statements and Assignment Expressions 10. is the Java assignment operator. a. == b. := c. = d. =: Key:c See the first paragraph. # 11. To assign a value 1 to variable x, you write a. 1 = x; b. x = 1; c. x := 1; d. 1 := x; e. x == 1; Key:b See the first paragraph. # 12. Which of the following assignment statements is incorrect? a. i = j = k = 1; b. i = 1; j = 1; k = 1; c. i = 1 = j = 1 = k = 1; d. i == j == k == 1; Key:cd Read toward the end of the section. # Section 2.7 Named Constants 13. To declare a constant MAX_LENGTH inside a method with value 99.98, you write a. final MAX_LENGTH = 99.98; b. final float MAX_LENGTH = 99.98; c. double MAX_LENGTH = 99.98; d. final double MAX_LENGTH = 99.98; Key:d See the first paragraph. # 14. Which of the following is a constant, according to Java naming conventions? a. MAX_VALUE b. Test c. read d. ReadInt e. COUNT Key:ae All letters in a constant are in uppercase. In a multiple-word constant, the words are connected using underscores. # 15. To improve readability and maintainability, you should declare a such as 3.14159. a. variable b. method ..

for PI instead of using literal values

c. constant d. class Key:c A constant gives a literal a descriptive name and makes the code more readable. # Section 2.8 Naming Conventions 16. According to Java naming convention, which of the following names can be variables? a. FindArea b. findArea c. totalLength d. TOTAL_LENGTH e. class Key:bc The first word in a variable is in lowercase. So B and C are correct. # Section 2.9 Numeric Data Types and Operations 17. Which of these data types requires the most amount of memory? a. long b. int c. short d. byte Key:a long takes 8 bytes. int 4 bytes. short 2 bytes. byte 1 byte. # Section 2.9.2 Numeric Operators 19. What is the result of 45 / 4? a. 10 b. 11 c. 11.25 d. 12 Key:b The result of the division is the quotient and the fractional part is truncated. So 45 / 4 is 11. 3 / 2 is 1, and so on. # 20. Which of the following expression results in a value 1? a. 2 % 1 b. 15 % 4 c. 25 % 5 d. 37 % 6 Key:d 2 % 1 is 0, 15 % 4 is 3, 25 % 5 is 0, and 37 % 6 is 1 # 21. 25 % 1 is a. 1 b. 2 c. 3 d. 4 e. 0 Key:e The reminder of any integer by 1 is 0. # 22. -25 % 5 is a. 1 b. 2 c. 3 ..

d. 4 e. 0 Key:e # 23. 24 % 5 is a. 1 b. 2 c. 3 d. 4 e. 0 Key:d # 24. -24 % 5 is a. -1 b. -2 c. -3 d. -4 e. 0 Key:d # 25. -24 % -5 is a. 3 b. -3 c. 4 d. -4 e. 0 Key:d # Section 2.9.3 Exponent Operations 26. How do you write 2.5 ^ 3.1 in Java? a. 2.5 * 3.1 b. Math.pow(2.5, 3.1) c. Math.pow(3.1, 2.5) d. 2.5 ** 3.1 e. 3.1 ** 2.5 Key:b See the first paragraph of the section. # 27. Math.pow(2, 3) returns a. 9 b. 8 c. 9.0 d. 8.0 Key:d It returns a double value 8.0. # 28. Math.pow(4, 1 / 2) returns a. 2 b. 2.0 c. 0 ..

d. 1.0 e. 1 Key:d Note that 1 / 2 is 0. # 29. Math.pow(4, 1.0 / 2) returns . a. 2 b. 2.0 c. 0 d. 1.0 e. 1 Key:b Note that the pow method returns a double value, not an integer. # 30. The method returns a raised to the power of b. a. Math.power(a, b) b. Math.exponent(a, b) c. Math.pow(a, b) d. Math.pow(b, a) Key:c See line 1 in Section 2.9.3. # Section 2.10 Numeric Literals 32. Analyze the following code. public class Test { public static void main(String[] args) { int month = 09; System.out.println("month is " + month); } } a. The program displays month is 09. b. The program displays month is 9. c. The program displays month is 9.0. d. The program has a syntax error, because 09 is an incorrect literal value. Key:d Any numeric literal with the prefix 0 is an octal value. But 9 is not an octal digit. An octal digit is 0, 1, 2, 3, 4, 5, 6, or 7. # 33. Which of the following is incorrect? a. 1_2 b. 0.4_56 c. 1_200_229 d. _4544 Key:d You can use the digit separator _ for integers or floating point numbers. The separator must be placed between the digits. # 34. Which of the following are the same as 1545.534? a. 1.545534e+3 b. 0.1545534e+4 c. 1545534.0e-3 d. 154553.4e-2 Key:abcd See Section 2.10.3. ..

# 31. To declare an int variable number with initial value 2, you write a. int number = 2L; b. int number = 2l; c. int number = 2; d. int number = 2.0; Key:c See Section 2.10.1. # 35. Which of the following is incorrect? a. int x = 9; b. long x = 9; c. float x = 1.0; d. double x = 1.0; Key:c Section 2.10.2. # Section 2.11 Prototyping Using JShell 31. The command to exit JShell is a. \quit b. \exit c. /quit d. /exit Key:d Read toward the end of this section.

# 31. The command to view all variables in JShell is a. \vars b. \var c. /vars d. /var Key:c See Figure 2.5.

# Section 2.12 Evaluating Expressions and Operator Precedence 36. The expression 4 + 20 / (3 - 1) * 2 is evaluated to a. 4 b. 20 c. 24 d. 9 e. 25 Key:c See the second paragraph in this section. # Section 2.13 Case Study: Displaying the Current Time 37. The System.currentTimeMillis() returns . a. the current time. b. the current time in milliseconds. c. the current time in milliseconds since midnight. d. the current time in milliseconds since midnight, January 1, 1970. e. the current time in milliseconds since midnight, January 1, 1970 GMT (the Unix time). Key:e See Listing 2.7.

# 38. To obtain the current second, use . a. System.currentTimeMillis() % 3600 b. System.currentTimeMillis() % 60 c. System.currentTimeMillis() / 1000 % 60 d. System.currentTimeMillis() / 1000 / 60 % 60 e. System.currentTimeMillis() / 1000 / 60 / 60 % 24 Key:c See Listing 2.7. # 39. To obtain the current minute, use . a. System.currentTimeMillis() % 3600 b. System.currentTimeMillis() % 60 c. System.currentTimeMillis() / 1000 % 60 d. System.currentTimeMillis() / 1000 / 60 % 60 e. System.currentTimeMillis() / 1000 / 60 / 60 % 24 Key:d See Listing 2.7. # 40. To obtain the current hour in UTC, use . a. System.currentTimeMillis() % 3600 b. System.currentTimeMillis() % 60 c. System.currentTimeMillis() / 1000 % 60 d. System.currentTimeMillis() / 1000 / 60 % 60 e. System.currentTimeMillis() / 1000 / 60 / 60 % 24 Key:e See Listing 2.7. # Section 2.14 Augmented Assignment Operators 43. Suppose x is 1. What is x after x += 2? a. 0 b. 1 c. 2 d. 3 e. 4 Key:d See Table 2.4 # 44. Suppose x is 1. What is x after x -= 1? a. 0 b. 1 c. 2 d. -1 e. -2 Key:a See Table 2.4 # 45.

What is x after the following statements?

int x = 2; int y = 1; x *= y + 1; a. x is 1. ..

b. x is 2. c. x is 3. d. x is 4. Key:d (y + 1) is executed first and its result is multiplied with x and assigned to x. # 46.

What is x after the following statements?

int x = 1; x *= x + 1; a. x is 1. b. x is 2. c. x is 3. d. x is 4. Key:b See Table 2.4. # 47.

Which of the following statements are the same?

(A) x -= x + 4 (B) x = x + 4 - x (C) x = x - (x + 4) a. (A) and (B) are the same b. (A) and (C) are the same c. (B) and (C) are the same d. (A), (B), and (C) are the same Key:b See Table 2.4. # 41. To add a value 1 to variable x, you write a. 1 + x = x; b. x += 1; c. x := 1; d. x = x + 1; e. x = 1 + x; Key:bde See Table 2.4. # 42. To add number to sum, you write (Note: Java is case-sensitive) a. number += sum; b. number = sum + number; c. sum = Number + sum; d. sum += number; e. sum = sum + number; Key:de See Table 2.4. # Section 2.15 Increment and Decrement Operators 49. What is i printed? public class Test { public static void main(String[] args) { ..

int j = 0; int i = ++j + j * 5; System.out.println("What is i? " + i); } } a. 0 b. 1 c. 5 d. 6 Key:d Operands are evaluated from left to right in Java. The left-hand operand of a binary operator is evaluated before any part of the right-hand operand is evaluated. This rule takes precedence over any other rules that govern expressions. Therefore, ++j is evaluated first, and j is now 1. Then j * 5 is evaluated, returns 5. So, i is 6. # 50. What is i printed in the following code? public class Test { public static void main(String[] args) { int j = 0; int i = j++ + j * 5; System.out.println("What is i? " + i); } } a. 0 b. 1 c. 5 d. 6 Key:c Operands are evaluated from left to right in Java. The left-hand operand of a binary operator is evaluated before any part of the right-hand operand is evaluated. This rule takes precedence over any other rules that govern expressions. Therefore, j++ is evaluated first. j is now 1. Since j++ is postincrement, the old value of j is returned for j++. So j++ + j * 5 equals 0 + 1 * 5. So, the result is 5. # 51. What is y displayed in the following code? public class Test { public static void main(String[] args) { int x = 1; int y = x++ + x; System.out.println("y is " + y); } } a. y is 1. b. y is 2. c. y is 3. d. y is 4. Key:c When evaluating x++ + x, x++ is evaluated first, which does two things: 1. returns 1 since it is post-increment. x becomes 2. Therefore y is 1 + 2. # 52. What is y displayed?

public class Test { public static void main(String[] args) { int x = 1; int y = x + x++; System.out.println("y is " + y); } } a. y is 1. b. y is 2. c. y is 3. d. y is 4. Key:b When evaluating x + x++, x is evaluated first, which is 1. X++ returns 1 since it is post-increment and 2. Therefore y is 1 + 1. # 48.

Are the following four statements equivalent?

number += 1; number = number + 1; number++; ++number; a. Yes b. No Key:a See Table 2.5. # Section 2.16 Numeric Type Conversions 53. To assign a double variable d to a float variable x, you write a. x = (long)d b. x = (int)d; c. x = d; d. x = (float)d; Key:d See the second paragraph in this section. # 54. Which of the following expressions will yield 0.5? a. 1 / 2 b. 1.0 / 2 c. (double) (1 / 2) d. (double) 1 / 2 e. 1 / 2.0 Key:bde 1 / 2 is an integer division, which results in 0. # 55. What is the output of the following code: double x = 5.5; int y = (int)x; System.out.println("x is " + x + " and y is " + y); a. x is 5 and y is 6 b. x is 6.0 and y is 6.0 c. x is 6 and y is 6 d. x is 5.5 and y is 5 e. x is 5.5 and y is 5.0 ..

Key:d The value is x is not changed after the casting. # 56. Which of the following assignment statements is illegal? a. float f = -34; b. int t = 23; c. short s = 10; d. int t = 4.5; Key:d See the second paragraph in this section. # 57. What is the value of (double)5/2? a. 2 b. 2.5 c. 3 d. 2.0 e. 3.0 Key:b See the second code box in this section. # 58. What is the value of (double)(5/2)? a. 2 b. 2.5 c. 3 d. 2.0 e. 3.0 Key:d See the second paragraph in this section. # 59. Which of the following expression results in 45.37? a. (int)(45.378 * 100) / 100 b. (int)(45.378 * 100) / 100.0 c. (int)(45.378 * 100 / 100) d. (int)(45.378) * 100 / 100.0 Key:b See Listing 2.8. # 60. The expression (int)(76.0252175 * 100) / 100 evaluates to a. 76.02 b. 76 c. 76.0252175 d. 76.03 Key:b In order to obtain 76.02, you have divide 100.0.

# 61. If you attempt to add an int, a byte, a long, and a double, the result will be a(n) a. byte b. int c. long d. double Key:d See the second paragraph in this section. # Section 2.17 Software Life Cycle ..

value.

62. is a formal process that seeks to understand the problem and document in detail what the software system needs to do. a. Requirements specification b. Analysis c. Design d. Implementation e. Testing Key:a See the second paragraph in this section. # 63. seeks to analyze the data flow and to identify the system’s input and output. When you do analysis, it helps to identify what the output is first, and then figure out what input data you need in order to produce the output. a. Requirements specification b. Analysis c. Design d. Implementation e. Testing Key:b See the third paragraph in this section. # Section 2.18 Case Study: Counting Monetary 62. Suppose int x = 3264, what is the output of the following code? int y = x % 10; x = x / 10; System.out.println("x is " + x + " and y is " + y); a. x is 3264 and y is 326.4 b. x is 326 and y is 326 c. x is 326 and y is 4 d. x is 3264 and y is 4 e. x is 4 and y is 326 Key:c 3264 / 10 is 326 and 3264 % 10 is 4. # Section 2.19 Common Errors and Pitfalls 64. Analyze the following code: public class Test { public static void main(String[] args) { int n = 10000 * 10000 * 10000; System.out.println("n is " + n); } } a. The program displays n is 1000000000000. b. The result of 10000 * 10000 * 10000 is too large to be stored in an int variable n. This causes an overflow and the program is aborted. c. The result of 10000 * 10000 * 10000 is too large to be stored in an int variable n. This causes an overflow and the program continues to execute because Java does not report errors on overflow. d. The result of 10000 * 10000 * 10000 is too large to be stored in an int variable n. This causes an underflow and the program is aborted. e. The result of 10000 * 10000 * 10000 is too large to be stored in an int variable n. This causes an underflow and the program continues to execute because Java does not report errors on underflow. ..

Key:c See Common Error 2: Integer Overflow. # 18. When assigning a literal to a variable of the byte type, if the literal is too large to be stored as a byte value, it . a. causes overflow b. causes underflow c. causes no error d. cannot happen in Java e. receives a compile error Key:e For example, byte b = 23232 will cause a compile error.

Chapter 3 Selections Section 3.2 boolean Data Type 1. The "less than or equal to" comparison operator in Java is . a. < b. <= c. =< d. << e. != Key:b It reads less than or equal to. So write the less than symbol before the equal sign. Note that there is no space separating the two symbols. # 2. The equal comparison operator in Java is . a. <> b. != c. == d. ^= Key:c Note that there is no space separating the double equal signs. # 3. What is 1 + 1 + 1 + 1 + 1 == 5? a. true b. false c. There is no guarantee that 1 + 1 + 1 + 1 + 1 == 5 is true. Key:a These are all integers. Integer arithmetic is accurate. # 4. What is 1 - 0.1 - 0.1 - 0.1 - 0.1 - 0.1 == 0.5? a. true b. false c. There is no guarantee that 1 - 0.1 - 0.1 - 0.1 - 0.1 - 0.1 == 0.5 is true. Key:c This epression involves floating-point number. Floating-point numbers are approximated. The correct answer is C. # 5. In Java, the word true is . a. a Java keyword b. a Boolean literal c. same as value 1 d. same as value 0 Key:b true is a Boolean literal just like integer literal 10. # Section 3.3 if Statements 6. Which of the following code displays the area of a circle if the radius is positive? a. if (radius != 0) System.out.println(radius * radius * 3.14159); b. if (radius >= 0) System.out.println(radius * radius * 3.14159); c. if (radius > 0) System.out.println(radius * radius * 3.14159); d. if (radius <= 0) System.out.println(radius * radius * 3.14159); key:c Positive means > 0. # ..

7. What is the output of the following code? int x = 0; if (x < 4) { x = x + 1; } System.out.println("x is " + x); a. x is 0 b. x is 1 c. x is 2 d. x is 3 e. x is 4 Key:b Since x is 0 before the if statement, x < 4 is true, x becomes 1 after the statement x = x + 1. The correct answer is B. # Section 3.4 Two-Way if-else Statements 8. Suppose income is 4001, what is the output of the following code? if (income > 3000) { System.out.println("Income is greater than 3000"); } else if (income > 4000) { System.out.println("Income is greater than 4000"); } a. no output b. Income is greater than 3000 c. Income is greater than 3000 followed by Income is greater than 4000 d. Income is greater than 4000 e. Income is greater than 4000 followed by Income is greater than 3000 Key:b Since income is 4001, the condition (income > 3000) is true. So statement for the true case is executed. # Section 3.5 Nested if and Multi-Way if-else Statements 9. The following code displays . double temperature = 50; if (temperature >= 100) System.out.println("too hot"); else if (temperature <= 40) System.out.println("too cold"); else System.out.println("just right"); a. too hot b. too cold c. just right d. too hot too cold just right Key:c The statement first test if (temperature >= 100). It is false. Then it tests if (temperature <= 4). It is false. So, it falls to the last else clause. The correct answer is C. # ..

Section 3.6 Common Errors and Pitfalls 10. Suppose x = 1, y = -1, and z = 1. What is the output of the following statement? (Please indent the statement correctly first.) if (x > 0) if (y > 0) System.out.println("x > 0 and y > 0"); else if (z > 0) System.out.println("x < 0 and z > 0"); a. x > 0 and y > 0; b. x < 0 and z > 0; c. x < 0 and z < 0; d. no output. Key:b You may copy the code to an IDE such as NetBeans or Eclipse and reformat it to see how it is correctly indented. The else clause matches the most recent if clause. So, it actually displays x < 0 and z > 0. # 11.

Analyze the following code:

boolean even = false; if (even = true) { System.out.println("It is even"); } a. The program has a compile error. b. The program has a runtime error. c. The program runs fine, but displays nothing. d. The program runs fine and displays It is even. Key:d It is a common mistake to use the = operator in the condition test. What happens is that true is assigned to even when you write even = true. So even is true. The program compiles and runs fine and displays "It is even". # 12. Suppose isPrime is a boolean variable, which of the following is the correct and best statement for testing if isPrime is true? a. if (isPrime = true) b. if (isPrime == true) c. if (isPrime) d. if (!isPrime = false) e. if (!isPrime == false) Key:c A and D are incorrect. B, C, and E are correct. But C is the simplest and thus the best. # 13. Analyze the following code. boolean even = false; if (even) { System.out.println("It is even!"); } a. The code displays It is even! b. The code displays nothing. c. The code is wrong. You should replace if (even) with if (even == true). d. The code is wrong. You should replace if (even) with if (even = true). Key:b Since even is false, the if statement body is not executed. So, the correct answer is B.

# 14.

Analyze the following code:

Code 1: int number = 45; boolean even; if (number % 2 == 0) even = true; else even = false; Code 2: int number = 45; boolean even = (number % 2 == 0); a. Code 1 has compile errors. b. Code 2 has compile errors. c. Both Code 1 and Code 2 have compile errors. d. Both Code 1 and Code 2 are correct, but Code 2 is better. Key:d Both Code 1 and Code 2 are correct. Clearly Code 2 is shorter and better. # Section 3.7 Generating Random Numbers 15. Which of the following is a possible output from invoking Math.random()? a. 3.43 b. 0.5 c. 0.0 d. 1.0 Key:bc Math.random() returns a real value between 0.0 and 1.0, excluding 1.0. # 16. What is the output from System.out.println((int)Math.random() * 4)? a. 0 b. 1 c. 2 d. 3 e. 4 Key:a Casting is performed before the * operator in (int)Math.random() * 4. So, it returns 0. # 17. What is the possible output from System.out.println((int)(Math.random() * 4))? a. 0 b. 1 c. 2 d. 3 e. 4 Key:abcd Math.random() returns a real value between 0.0 and 1.0, excluding 1.0. Math.random() * 4 yields a real value between 0.0 and 4.0, excluding 4.0. After casting, the resulting integer may be 0, 1, 2, or 3. # Section 3.8 Case Study: Computing Body Mass Index 18. Suppose you write the code to display "Cannot get a driver's license" if age is less than 16 and "Can get a driver's ..

license" if age is greater than or equal to 16. Which of the following code is correct? I: if (age < 16) System.out.println("Cannot get a driver's license"); if (age >= 16) System.out.println("Can get a driver's license"); II: if (age < 16) System.out.println("Cannot get a driver's license"); else System.out.println("Can get a driver's license"); III: if (age < 16) System.out.println("Cannot get a driver's license"); else if (age >= 16) System.out.println("Can get a driver's license"); IV: if (age < 16) System.out.println("Cannot get a driver's license"); else if (age > 16) System.out.println("Can get a driver's license"); else if (age == 16) System.out.println("Can get a driver's license"); a. I b. II c. III d. IV Key:abcd All the statements are correct. II is the best. # 19. Suppose you write the code to display "Cannot get a driver's license" if age is less than 16 and "Can get a driver's license" if age is greater than or equal to 16. Which of the following code is the best? I: if (age < 16) System.out.println("Cannot get a driver's license"); if (age >= 16) System.out.println("Can get a driver's license"); II: if (age < 16) System.out.println("Cannot get a driver's license"); else System.out.println("Can get a driver's license"); III: if (age < 16) System.out.println("Cannot get a driver's license"); else if (age >= 16) ..

System.out.println("Can get a driver's license"); IV: if (age < 16) System.out.println("Cannot get a driver's license"); else if (age > 16) System.out.println("Can get a driver's license"); else if (age == 16) System.out.println("Can get a driver's license"); a. I b. II c. III d. IV Key:b All the statements are correct. II is the best. # Section 3.9 Case Study: Computing Taxes 20. The method immediately terminates the program. a. System.terminate(0); b. System.halt(0); c. System.exit(0); d. System.quit(0); e. System.stop(0); Key:c System.exit(0) method can be used to terminate a program. # Section 3.10 Logical Operators 21. Which of the Boolean expressions below is incorrect? a. (true) && (3 => 4) b. !(x > 0) && (x > 0) c. (x > 0) || (x < 0) d. (x != 0) || (x = 0) e. (-10 < x < 0) Key:ade a: (3 => 4) should be (3 >= 4), d: (x = 0) should be (x == 0), and e: should be (-10 < x) && (x < 0) # 22. Which of the following is the correct expression that evaluates to true if the number x is between 1 and 100 or the number is negative? a. 1 < x < 100 && x < 0 b. ((x < 100) && (x > 1)) || (x < 0) c. ((x < 100) && (x > 1)) && (x < 0) d. (1 > x > 100) || (x < 0) Key:b A and D have syntax errors. B uses || for the OR operator. The correct answer is B. # 23. Assume x = 4 and y = 5, which of the following is true? a. x < 5 && y < 5 b. x < 5 || y < 5 c. x > 5 && y > 5 d. x > 5 || y > 5 Key:b x < 5 is true, but y < 5 is false. So A is false. B is true. C and D are both false, because x > 5 is false and y > 5 is false. The correct answer is B.

# 24. Assume x = 4, which of the following is true? a. !(x == 4) b. x != 4 c. x == 5 d. x != 5 Key:d D is true. All others are false. # 25. Assume x = 4 and y = 5, which of the following is true? a. !(x == 4) ^ y != 5 b. x != 4 ^ y == 5 c. x == 5 ^ y == 4 d. x != 5 ^ y != 4 Key:b x != 4 is false and y == 5 is true. So B is correct. # Section 3.11 Determining Leap Year 26. Given |x| <= 4, which of the following is true? a. x <= 4 && x >= 4 b. x <= 4 && x > -4 c. x <= 4 && x >= -4 d. x <= 4 || x >= -4 Key:c |x| <= 4 means -4 <= x <= 4. That is x <= 4 and x >= -4. |x| <= 4 is true for x being -4, -3, 0, 2, 4, etc. So the correct answer is C. # 27. Given |x| >= 4, which of the following is true? a. x >= 4 && x <= -4 b. x >= 4 || x <= -4 c. x >= 4 && x < -4 d. x >= 4 || x < -4 Key:b |x| >= 4 means x >= 4 or x <= -4. |x| >= 4 is true for x being -4, -5, -6, 4, 5, 6, etc. So B is correct. # 28. Which of the following is equivalent to x != y? a. ! (x == y) b. x > y && x < y c. x > y || x < y d. x >= y || x <= y Key:ac x != y means !(x == y) and x > y || x < y. # Section 3.12 Lottery 29. Suppose x=10 and y=10. What is x after evaluating the expression (y > 10) && (x-- > 10)? a. 9 b. 10 c. 11 Key:b For the && operator, the right operand is not evaluated, if the left operand is evaluated as false. # 30. a. b. ..

Suppose x=10 and y=10. What is x after evaluating the expression (y > 10) && (x++ > 10). 9 10

c. 11 Key:b For the && operator, the right operand is not evaluated, if the left operand is evaluated as false. # 31. Suppose x=10 and y=10. What is x after evaluating the expression (y >= 10) || (x-- > 10). a. 9 b. 10 c. 11 Key:b For the || operator, the right operand is not evaluated, if the left operand is evaluated as true. # 32. Suppose x=10 and y=10. What is x after evaluating the expression (y >= 10) || (x++ > 10). a. 9 b. 10 c. 11 Key:b For the || operator, the right operand is not evaluated, if the left operand is evaluated as true. # 33. Analyze the following code: if (x < 100) && (x > 10) System.out.println("x is between 10 and 100"); a. The statement has compile errors because (x<100) & (x > 10) must be enclosed inside parentheses. b.The statement has compile errors because (x<100) & (x > 10) must be enclosed inside parentheses and the println(…) statement must be put inside a block. c.The statement compiles fine. d.The statement compiles fine, but has a runtime error. Key:a The condition for an if statement must be enclosed in the parentheses. The correct answer is A. # 34. Which of the following are so called short-circuit operators? a. && b. & c. || d. | Key:ac && and || are short-circuit operator, meaning that if the left operand can determine the result of the operation, the right operand will be skipped. # Section 3.13 switch Statements 35. What is y after the following switch statement is executed? int x = 3; int y = 4; switch (x + 3) { case 6: y = 0; case 7: y = 1; default: y += 1; } a. 1 b. 2 c. 3 d. 4 e. 0 Key:b Since x is 3, x + 3 is 6. So, case 6 is executed. Since there is no break statement, the statement in the next case is ..

executed. y is now 1. Finally y += 1 adds 1 to y. So y is 2. The correct answer is B. # 36.

Analyze the following program fragment:

int x; double d = 1.5; switch (d) { case 1.0: x = 1; case 1.5: x = 2; case 2.0: x = 3; } a. The program has a compile error because the required break statement is missing in the switch statement. b. The program has a compile error because the required default case is missing in the switch statement. c. The switch control variable cannot be double. d. No errors. Key:c The switch value cannot be a floating-point number. So the correct answer is C. # Section 3.14 Conditional Expressions 37. What is y after the following statement is executed? x = 0; y = (x > 0) ? 10 : -10; a. -10 b. 0 c. 10 d. 20 e. Illegal expression Key:a This conditional operator is correct. It assigns -10 to y since x > 0 is false. # 38.

Analyze the following code fragments that assign a boolean value to the variable even.

Code 1: if (number % 2 == 0) even = true; else even = false; Code 2: even = (number % 2 == 0) ? true: false; Code 3: even = number % 2 == 0; a. Code 2 has a compile error, because you cannot have true and false literals in the conditional expression. b. Code 3 has a compile error, because you attempt to assign number to even. c. All three are correct, but Code 1 is preferred. d. All three are correct, but Code 2 is preferred. e. All three are correct, but Code 3 is preferred. Key:e Code 3 is the simplest. Code 1 and Code 2 contain redundant code. # ..

39. What is the output of the following code? boolean even = false; System.out.println((even ? "true" : "false")); a. true b. false c. nothing d. true false Key:b Since even is false, the conditional expression yields false. The correct answer is B. # Section 3.15 Operator Precedence and Associativity 40. The order of the precedence (from high to low) of the operators binary +, *, &&, ||, ^ is: a. &&, ||, ^, *, + b. *, +, &&, ||, ^ c. *, +, ^, &&, || d. *, +, ^, ||, && e. ^, ||, &&, *, + Key:c See the table for the operator precedence order. The correct answer is C. # 41. What is y displayed in the following code? public class Test1 { public static void main(String[] args) { int x = 1; int y = x = x + 1; System.out.println("y is " + y); } } a. y is 0. b. y is 1 because x is assigned to y first. c. y is 2 because x + 1 is assigned to x and then x is assigned to y. d. The program has a compile error since x is redeclared in the statement int y = x = x + 1. Key:c The = operator is right-associative. # 42. Which of the following operators are right-associative. a. * b. + (binary +) c. % d. && e. = Key:e Assignment operators including augmented assignment operators are right-associative. The correct answer is E. # 43. What is the value of the following expression? true || true && false a. true b. false Key:a && has higher precedence than ||, so && is evaluated first. # ..

44. Which of the following statements are true? a. (x > 0 && x < 10) is same as ((x > 0) && (x < 10)) b. (x > 0 || x < 10) is same as ((x > 0) || (x < 10)) c. (x > 0 || x < 10 && y < 0) is same as (x > 0 || (x < 10 && y < 0)) d. (x > 0 || x < 10 && y < 0) is same as ((x > 0 || x < 10) && y < 0) Key:abc In D, && is evaluated before the || operator. So (x > 0 || x < 10 && y < 0) is not same as ((x > 0 || x < 10) && y < 0).

Chapter 4 Mathematical Functions, Characters, and Strings Section 4.2 Common Mathematical Functions Section 4.2.1 Trigonometric Methods 1. To obtain the sine of 35 degrees, use . a. Math.sin(35) b. Math.sin(Math.toRadians(35)) c. Math.sin(Math.toDegrees(35)) d. Math.sin(Math.toRadian(35)) e. Math.sin(Math.toDegree(35)) Key:b Note the trig methods use the radians for angles. # 2. To obtain the arc sine of 0.5, use . a. Math.asin(0.5) b. Math.asin(Math.toDegrees(0.5)) c. Math.sin(Math.toRadians(0.5)) d. Math.sin(0.5) Key:a Note the trig methods use the radians for angles. # 3. Math.asin(0.5) returns . a. 30 b. Math.toRadians(30) c. Math.PI / 4 d. Math.PI / 2 Key:b Note that Math.asin returns an angle in radians. # 4. Math.sin(Math.PI) returns . a. 0.0 b. 1.0 c. 0.5 d. 0.4 Key:a Note that Math.PI is 180 degrees. # 5. Math.cos(Math.PI) returns . a. 0.0 b. 1.0 c. -1.0 d. 0.5 Key:c Note that Math.PI is 180 degrees. # Section 4.2.2 Exponent Methods 1. Which of the following is correct to obtain the square of 5? a. Math.sqrt(5) b. Math.sqrt(5.0) c. Math.pow(5, 0.5) d. Math.pow(5.0, 0.5) Key:abcd All choices are correct. © 2020 Pearson Education, Inc., Hoboken, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist.

# Section 4.2.3 The Rounding Methods 6. What is Math.rint(3.6)? a. 3.0 b. 3 c. 4.0 d. 5.0 Key:c Note that rint returns a double value # 5. What is Math.round(3.6)? a. 3.0 b. 3 c. 4 d. 4.0 Key:c Note that round returns an int value # 7. What is Math.rint(3.5)? a. 3.0 b. 3 c. 4 d. 4.0 e. 5.0 Key:d rint returns the nearest even integer as a double since 3.5 is equally close to 3.0 and 4.0. # 8. What is Math.ceil(3.6)? a. 3.0 b. 3 c. 4.0 d. 5.0 Key:c Note that ceil returns a double value # 9. What is Math.floor(3.6)? a. 3.0 b. 3 c. 4 d. 5.0 Key:a Note that floor returns a double value # Section 4.2.4 The min, max, and abs Methods 1. Which of the following is correct to obtain the min of x, y, z? a. Math.min(x, Math.min(y, z)) b. Math.min(Math.min(x, y), z) c. Math.min(Math.min(y, z), x) d. Math.min(z, Math.min(x, y)) Key:abcd All choices are correct. # Section 4.2.5 The random Method 1. Which of the following is correct to obtain a random integer between 5 and 10? © 2020 Pearson Education, Inc., Hoboken, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist.

a. 5 + Math.random() * 6 b. 5 + (int)(Math.random() * 6) c. 5 + Math.random() * 5 d. 5 + (int)(Math.random() * 5) Key:b In A, 5 + Math.random() * 6 returns a double value from 5.0 to 11.0 (excluding 11.0). In C, 5 + Math.random() * 5 returns a double value from 5.0 to 10.0 (excluding 10.0). In D, 5 + (int)(Math.random() * 5) returns an integer from 5 to 10. B is correct. # Section 4.3 Character Data Type and Operations Section 4.3.1 Unicode and ASCII Code 10. Which of the following is the correct expression of character 4? a. 4 b. "4" c. '\0004' d. '4' Key:d You have to write '4'. # 11. A Java character is stored in . a. one byte b. two bytes c. three bytes d. four bytes Key:b Java characters use Unicode encoding. # 12. The Unicode of 'a' is 97. What is the Unicode for 'c'? a. 96 b. 97 c. 98 d. 99 Key:d The Unicode for letters and numbers are allocated in a natural order. So b is after a and c is after b, and so on. # Section 4.3.2 Escape Sequences for Special Characters 13. Which of the following statement prints smith\exam1\test.txt? a. System.out.println("smith\exam1\test.txt"); b. System.out.println("smith\\exam1\\test.txt"); c. System.out.println("smith\"exam1\"test.txt"); d. System.out.println("smith"\exam1"\test.txt"); Key:b To represent the \ character, use \\, because it is an escape character. # Section 4.3.3 Casting between char and Numeric Types 14. Suppose x is a char variable with a value 'b'. What is the output of the statement System.out.println(++x)? a. a b. b c. c d. d Key:c The ++ and -- operators can be applied to a char variable. ++x is preincrement. x is 'b' before ++x. After ++x, x becomes c. #

15. Suppose i is an int type variable. Which of the following statements display the character whose Unicode is stored in variable i? a. System.out.println(i); b. System.out.println((char)i); c. System.out.println((int)i); d. System.out.println(i + " "); Key:b (char)i casts a number into a character. # 16. Will System.out.println((char)4) display 4? a. Yes b. No Key:b The character whose Unicode is \u0004 is to be displayed, not number 4. # 17. What is the output of System.out.println('z' - 'a')? a. 25 b. 26 c. a d. z Key:a The Unicode offset between z and a is 25. # 18. An int variable can hold . a. 'x' b. 120 c. 120.0 d. "x" e. "120" Key:ab Choice A is also correct, because a character can be implicitly cast into an int variable. The Unicode value of character is assignment to the int variable. In this case, the code is 120 (see Appendix B). # 19. Which of the following assignment statements is correct? a. char c = 'd'; b. char c = 100; c. char c = "d"; d. char c = "100"; Key:ab Choice B is also correct, because an int value can be implicitly cast into a char variable. The Unicode of the character is the int value. In this case, the character is d (see Appendix B). # 20. '3' - '2' + 'm' / 'n' is . a. 0 b. 1 c. 2 d. 3 Key:b When an operand is a character in an arithmetic expression, the character is casted to an int value. # Section 4.3.4 Comparing and Testing Characters 21. To check whether a char variable ch is an uppercase letter, you write a. (ch >= 'A' && ch >= 'Z') b. (ch >= 'A' && ch <= 'Z')

c. (ch >= 'A' || ch <= 'Z') d. ('A' <= ch <= 'Z') Key:b A is wrong because ch >= 'Z'. C is wrong because of using ||. D is wrong because of incorrect syntax. The correct answer is B. # 22. Which of the following is not a correct method in the Character class? a. isLetterOrDigit(char) b. isLetter(char) c. isDigit() d. toLowerCase(char) e. toUpperCase() Key:ce isDigit() should be isDigit(char) and toUpperCase() should be toUpperCase(char) # Section 4.4 The String Type Section 4.4.2 Gettiing Characters from a String 24. Suppose s is a string with the value "java". What will be assigned to x if you execute the following code? char x = s.charAt(4); a. 'a' b. 'v' c. Nothing will be assigned to x, because the execution causes the runtime error StringIndexOutofBoundsException. Key:c The string index starts from 0 and the last index is s.length() - 1. s.charAt(4) is out of bounds. # Section 4.4.3 Concatenating Strings 25. The expression "Java " + 1 + 2 + 3 evaluates to . a. Java123 b. Java6 c. Java 123 d. java 123 e. Illegal expression key:c The + operator is evaluated from left to right. When a string adds with a number, the number is converted into a string. The correct answer is C. # 26. Note that the Unicode for character A is 65. The expression "A" + 1 evaluates to . a. 66 b. B c. A1 d. Illegal expression key:c When a string adds with a number, the number is converted into a string. The correct answer is C. # 27. Note that the Unicode for character A is 65. The expression 'A' + 1 evaluates to . a. 66 b. B c. A1 d. Illegal expression key:a When a character adds with a number, the character is converted into a int. The correct answer is A. # Section 4.4.4 Converting Strings

28. Which of the following is the correct statement to return JAVA? a. toUpperCase("Java") b. "Java".toUpperCase("Java") c. "Java".toUpperCase() d. String.toUpperCase("Java") Key:c The correct method is toUpperCase(). So C is correct. # Section 4.4.7 Comparing Strings 29. Suppose s1 and s2 are two strings. Which of the following statements or expressions is incorrect? a. String s3 = s1 - s2; b. boolean b = s1.compareTo(s2); c. char c = s1[0]; d. char c = s1.charAt(s1.length()); Key:abcd A is wrong because the - operator cannot be used for strings. B is wrong because the compareTo method returns an int, not a boolean. C is wrong because the [] cannot be used for accessing string elements. D is wrong because of index out of bounds. # 30.

Suppose s1 and s2 are two strings. What is the result of the following code?

s1.equals(s2) == s2.equals(s1) a. true b. false Key:a s1.equals(s2) and s2.equals(s1) are the same. # 31. "abc".compareTo("aba") returns . a. 1 b. 2 c. -1 d. -2 e. 0 Key:b The first two characters in the two strings are the same. The different between the last two characters is 2. The correct answer is B. # 32. "AbA".compareToIgnoreCase("abC") returns . a. 1 b. 2 c. -1 d. -2 e. 0 Key:d Ignoring case, you compare aba with abc. The first two characters in the two strings are the same. The different between the last two characters is -2. The correct answer is D. # 33. returns true. a. "peter".compareToIgnoreCase("Peter") b. "peter".compareToIgnoreCase("peter") c. "peter".equalsIgnoreCase("Peter") d. "peter".equalsIgnoreCase("peter") e. "peter".equals("peter") Key:cde The compareToIgnoreCase return an int. So, A and B are wrong. Ignoring case, C, D, and E all return true.

# Section 4.4.8 Obtaining Substrings 34. What is the return value of "SELECT".substring(0, 5)? a. "SELECT" b. "SELEC" c. "SELE" d. "ELECT" Key:b Note that the substring is from index 0 to 4, which is 5 - 1. The correct answer is B. # 35. What is the return value of "SELECT".substring(4, 4)? a. an empty string b. C c. T d. E Key:a If beginIndex is endIndex, substring(beginIndex, endIndex) returns an empty string with length 0. It would be a runtime error, if beginIndex > endIndex. # Section 4.4.9 Finding a Character or a Substring in a String 36. To check if a string s contains the prefix "Java", you may write a. if (s.startsWith("Java")) ... b. if (s.indexOf("Java") == 0) ... c. if (s.substring(0, 4).equals("Java")) ... d. if (s.charAt(0) == 'J' && s.charAt(1) == 'a' && s.charAt(2) == 'v' && s.charAt(3) == 'a') ... Key:abcd They are all correct. # 37. To check if a string s contains the suffix "Java", you may write a. if (s.endsWith("Java")) ... b. if (s.lastIndexOf("Java") >= 0) ... c. if (s.substring(s.length() - 4).equals("Java")) ... d. if (s.substring(s.length() - 5).equals("Java")) ... e. if (s.charAt(s.length() - 4) == 'J' && s.charAt(s.length() - 3) == 'a' && s.charAt(s.length() - 2) == 'v' && s.charAt(s.length() - 1) == 'a') ... Key:ace s.lastIndexOf("Java") >= 0 does not indicate that Java is the suffix of the string. # Section 4.4.10 Conversions between Strings and Numbers 38. The method parses a string s to an int value. a. integer.parseInt(s); b. Integer.parseInt(s); c. integer.parseInteger(s); d. Integer.parseInteger(s); Key:b The parseInt method is defined in the Integer class. B is correct. # 39. The method parses a string s to a double value. a. double.parseDouble(s); b. Double.parsedouble(s); c. double.parse(s); d. Double.parseDouble(s);

Key:d The parseDouble method is defined in the Double class. D is correct. # Section 4.6 Formatting Console Output 40. Which of the following are valid specifiers for the printf statement? a. %4c b. %10b c. %6d d. %8.2d e. %10.2e Key:abce All correct. D is wrong because the specifier d is for decimal integer. # 41. The statement System.out.printf("%3.1f", 1234.56) outputs . a. 123.4 b. 123.5 c. 1234.5 d. 1234.56 e. 1234.6 Key:e .1 specifies one digit after the decimal point. The rest is rounded up. So 1234.56 is displayed 1234.6. # 42. The statement System.out.printf("%3.1e", 1234.56) outputs . a. 0.1e+04 b. 0.123456e+04 c. 0.123e+04 d. 1.2e+03 e. 1.23+03 Key:d %3.1e specifies a scientific notation with one digit after the decimal point. So, the correct answer is D. # 43. The statement System.out.printf("%5d", 123456) outputs . a. 12345 b. 23456 c. 123456 d. 12345.6 Key:c %5d specifies an integer with width 5. The width is automatically expanded if the number is larger than the specified width. So, the correct answer is C. # 44. The statement System.out.printf("%10s", 123456) outputs . (Note: * represents a space) a. 123456**** b. 23456***** c. 12345***** d. ****123456 Key:d %10s specifies to display a string with width 10. By default, it is right justified. So, the correct answer is D. # 45. Analyze the following code: int i = 3434; double d = 3434; System.out.printf("%5.1f %5.1f", i, d); a. The code compiles and runs fine to display 3434.0 3434.0.

b. The code compiles and runs fine to display 3434 3434.0. c. i is an integer, but the format specifier %5.1f specifies a format for double value. The code has an error. Key:c i is an integer, but the format specifier %5.1f specifies a format for double value. Type does not match. So, the correct answer is C.

Chapter 5 Loops Section 5.2 The while Loop 1. How many times will the following code print "Welcome to Java"? int count = 0; while (count < 10) { System.out.println("Welcome to Java"); count++; } a. 8 b. 9 c. 10 d. 11 e. 0 Key:c The count is initialized to 0 before the loop. The loop is executed 10 times for count from 1 to 9. When count is 10, the loop continuation condition becomes false. The loop is finished. So, the correct answer is C. # 2. Analyze the following code. int count = 0; while (count < 100) { // Point A System.out.println("Welcome to Java!"); count++; // Point B } // Point C a. count < 100 is always true at Point A b. count < 100 is always true at Point B c. count < 100 is always false at Point B d. count < 100 is always true at Point C e. count < 100 is always false at Point C Key:ae The count is initialized to 0 before the loop. The loop is executed 100 times for count from 0 to 99. Inside the loop body, at Point A, count < 100 is true. After executing count++, count < 100 in Point B may become false. After the loop is exited, count < 100 is false at Point C. So, the correct answer is AE. # Section 5.3 Case Study: Guessing Numbers 3. How many times will the following code print "Welcome to Java"? int count = 0; while (count++ < 10) { System.out.println("Welcome to Java"); } a. 8 b. 9 c. 10 d. 11 e. 0 Key:c The count is initialized to 0 before the loop. (count++ < 10) increments count by 1 and uses the old count value ..

to check if count < 10. So, the loop is executed 10 times for count from 0 to 9. The correct answer is C. # 4. What is the output of the following code? int x = 0; while (x < 4) { x = x + 1; } System.out.println("x is " + x); a. x is 0 b. x is 1 c. x is 2 d. x is 3 e. x is 4 Key:e x is 0 before the loop. The loop is executed 4 times for x from 0 to 3. When x is 4 the loop exits. So, the correct answer is E. # Section 5.5 Controlling a Loop with User Confirmation or a Sentinel Value 5. What will be displayed when the following code is executed? int number = 6; while (number > 0) { number -= 3; System.out.print(number + " "); } a. 630 b. 6 3 c. 30 d. 3 0 -3 e. 0 -3 Key:c number is 6 before the loop. In the first iteration, number is reduced to 3. In the second iteration, number is reduced to 0. The loop is now finished. The loop body is executed 2 times for number 6 and 3. Since number is reduced by 3 before the print statement. 3 and 0 and displayed. So, the correct answer is C. # Section 5.6 The do-while Loop 6. How many times will the following code print "Welcome to Java"? int count = 0; do { System.out.println("Welcome to Java"); count++; } while (count < 10); a. 8 b. 9 c. 10 d. 11 e. 0 Key:c The count is initialized to 0 before the loop. The loop is executed 10 times for count from 0 to 9. When count is 10, the loop continuation condition becomes false. The loop is finished. So, the correct answer is C.

# 7.

How many times will the following code print "Welcome to Java"?

int count = 0; do { System.out.println("Welcome to Java"); } while (count++ < 10); a. 8 b. 9 c. 10 d. 11 e. 0 Key:d The count is initialized to 0 before the loop. The loop is executed for the first time when count is 0. (count++ < 10) increments count by 1 and uses the old count value to check if count < 10. So, the loop is executed 11 times for count from 0 to 10. Note that when count is 10, the loop body is executed before the loop is exited. The correct answer is D. # 8.

How many times will the following code print "Welcome to Java"?

int count = 0; do { System.out.println("Welcome to Java"); } while (++count < 10); a. 8 b. 9 c. 10 d. 11 e. 0 Key:c The count is initialized to 0 before the loop. The loop is executed for the first time when count is 0. (++count < 10) increments count by 1 and uses the new count value to check if count < 10. So, the loop is executed 10 times for count from 0 to 9. Note that when count is 9, ++count becomes 10, the loop exits. The correct answer is C. # 9.

What is the value in count after the following loop is executed?

int count = 0; do { System.out.println("Welcome to Java"); } while (count++ < 9); System.out.println(count); a. 8 b. 9 c. 10 d. 11 e. 0 Key:c The count is initialized to 0 before the loop. The loop is executed for the first time when count is 0. (count++ < 9) increments count by 1 and uses the old count value to check if count < 9. So, the loop is executed 10 times for count from 0 to 9. Note that when count is 9, the loop body is executed and then count++ increments count to 10. The previous count value 9 < 9 is false. So the loop is finished. Now count becomes 10 after the loop exits. The correct answer is C. # Section 5.7 The for Loop ..

10.

Analyze the following statement:

double sum = 0; for (double d = 0; d < 10;) { d += 0.1; sum += sum + d; } a. The program has a compile error because the adjustment is missing in the for loop. b. The program has a compile error because the control variable in the for loop cannot be of the double type. c. The program runs in an infinite loop because d &lt; 10 would always be true. d. The program compiles and runs fine. Key:d In this loop, the loop initial action is d = 0, the continuation condition is d < 10, and the action-after-eachiteration is blank. Note that any of these three parts in the loop can be omitted. So, the loop is correct. The correction answer is (D). # 11. Which of the following loops prints "Welcome to Java" 10 times? A: for (int count = 1; count <= 10; count++) { System.out.println("Welcome to Java"); } B: for (int count = 0; count < 10; count++) { System.out.println("Welcome to Java"); } C: for (int count = 1; count < 10; count++) { System.out.println("Welcome to Java"); } D: for (int count = 0; count <= 10; count++) { System.out.println("Welcome to Java"); } a. BD b. ABC c. AC d. BC e. AB Key:e In (A), the loop displays Welcome to Java 10 times for count from 1 to 10. In (B), the loop displays Welcome to Java 10 times for count from 0 to 9. In (C), the loop displays Welcome to Java 9 times for count from 1 to 9. In (D), the loop displays Welcome to Java 11 times for count from 0 to 10. Therefore, the correct answer is AB. # 12. Which of the following loops correctly computes 1/2 + 2/3 + 3/4 + ... + 99/100? A: double sum = 0; for (int i = 1; i <= 99; i++) { sum = i / (i + 1); } ..

System.out.println("Sum is " + sum); B: double sum = 0; for (int i = 1; i < 99; i++) { sum += i / (i + 1); } System.out.println("Sum is " + sum); C: double sum = 0; for (int i = 1; i <= 99; i++) { sum += 1.0 * i / (i + 1); } System.out.println("Sum is " + sum); D: double sum = 0; for (int i = 1; i <= 99; i++) { sum += i / (i + 1.0); } System.out.println("Sum is " + sum); E: double sum = 0; for (int i = 1; i < 99; i++) { sum += i / (i + 1.0); } System.out.println("Sum is " + sum); a. BCD b. ABCD c. B d. CDE e. CD Key:e Note that 1 / 2 is 0.5 in a math expression. In Java, however, integer division yields an integer. The fraction part is truncated. Therefore, i / (i + 1) is 0. (A) and (B) are incorrect. (E) is incorrect because the last i in the loop is 98. So the last item 99 / 100.0 is not added to sum. So, the correct answer is CD. # 13. The following loop displays

for (int i = 1; i <= 10; i++) { System.out.print(i + " "); i++; } a. 1 2 3 4 5 6 7 8 9 b. 1 2 3 4 5 6 7 8 9 10 c. 1 2 3 4 5 d. 1 3 5 7 9 e. 2 4 6 8 10 Key:d In this for loop, i is initialized to 1. i++ adds 1 to i at the end of the iteration. In the action-after-each-iteration, i is again incremented by 1. So, i is in effect incremented twice. So, i is 1, then 3, 5, 7, and 9. The correct answer is D. ..

# 14.

Do the following two statements in (I) and (II) result in the same value in sum?

(I): for (int i = 0; i &lt; 10; ++i) { sum += i; } (II): for (int i = 0; i &lt; 10; i++) { sum += i; } a. Yes b. No Key:a In this case, ++i and i++ are used standalone with no side-effect. So, (I) and (II) are equivalent. The correct answer is A. # 15.

What is the output for y?

int y = 0; for (int i = 0; i &lt; 10; ++i) { y += i; } System.out.println(y); a. 10 b. 11 c. 12 d. 13 e. 45 Key:e The loop is executed 10 times for i from 0 to 9. Each time, i is added to y. So y = 0 + 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9, which 45. The correct answer is E. # 16.

What is i after the following for loop?

int y = 0; for (int i = 0; i &lt; 10; ++i) { y += i; } a. 9 b. 10 c. 11 d. undefined Key:d The scope for i is inside the loop. After the loop, i is not defined. So, the correct answer is D. # 17.

Is the following loop correct?

for ( ; ; ); a. Yes b. No ..

Key:a Yes. This is equivalent to for (; true; ). # Section 5.8 Which Loop to Use? 18. Analyze the following fragment: double sum = 0; double d = 0; while (d != 10.0) { d += 0.1; sum += sum + d; } a. The program does not compile because sum and d are declared double, but assigned with integer value 0. b. The program never stops because d is always 0.1 inside the loop. c. The program may not stop because of the phenomenon referred to as numerical inaccuracy for operating with floating-point numbers. d. After the loop, sum is 0 + 0.1 + 0.2 + 0.3 + ... + 1.9 Key:c The correct answer is C. There is no guarantee that d will be exactly 10.0 because real numbers are represented using approximation in a computer system. # 19. Analyze the following code: public class Test { public static void main (String[] args) { int i = 0; for (i = 0; i < 10; i++); System.out.println(i + 4); } } a. The program has a compile error because of the semicolon (;) on the for loop line. b. The program compiles despite the semicolon (;) on the for loop line, and displays 4. c. The program compiles despite the semicolon (;) on the for loop line, and displays 14. d. The for loop in this program is same as for (i = 0; i < 10; i++) { }; System.out.println(i + 4); Key:cd This is a logic error. System.out.println(i + 4) is not a part the for loop because the for loop ends with the last semicolon at for (i=0; i &lt; 10; i++); # Section 5.9 Nested Loops 20. How many times is the println statement executed? for (int i = 0; i < 10; i++) for (int j = 0; j < i; j++) System.out.println(i * j) a. 100 b. 20 c. 10 d. 45 Key:d When i is 0, the println statement is not executed. When i is 1, the println is executed 1 time. When i is 2, the println is executed 2 times. When i is 9, the println is executed 9 times. So, the total time for the println to be executed is 1 + 2 + ... + 9 = 45. # ..

21. Which pattern is produced by the following code? for (int i = 1; i <= 6; i++) { for (int j = 6; j >= 1; j--) System.out.print(j <= i ? j + " " : " " + " "); System.out.println(); } Pattern A Pattern B Pattern C Pattern D 1 123456 1 123456 12 12345 21 12345 123 1234 321 1234 1234 123 4321 123 12345 12 54321 12 123456 1 654321 1 a. Pattern A b. Pattern B c. Pattern C d. Pattern D Key:c The outer loop displays a line. The inner loop displays all the numbers in the line. The outer loop is repeated 6 times for i from 1 to 6. For each i, the inner loops displays i as the first number in the line since j is from 6 to 1. j is printed for j <= i. Otherwise, a space is printed. Clearly, this code will print Pattern C. # 22.

How many times is the println statement executed?

for (int i = 0; i < 10; i++) for (int j = 0; j < 10; j++) System.out.println(i * j); a. 100 b. 20 c. 10 d. 45 Key:a The outer loop is executed 10 times for i from 0 to 9 and the inner loop is executed 10 times from j from 0 to 9. So the print statement is executed 100 times. The correct answer is A. # Section 5.10 Minimizing Numerical Errors 23. To add 0.01 + 0.02 + ... + 1.00, what order should you use to add the numbers to get better accuracy? a. add 0.01, 0.02, ..., 1.00 in this order to a sum variable whose initial value is 0. b. add 1.00, 0.99, 0.98, ..., 0.02, 0.01 in this order to a sum variable whose initial value is 0. Key:a Adding the numbers in the order specified in A will result in a more accurate result than in B, because two numbers to be added will be about the same size. # 24.

Analyze the following code.

double sum = 0; for (double d = 0; d < 10; sum += sum + d) { d += 0.1; } ..

A. The program has a syntax error because the adjustment statement is incorrect in the for loop. B. The program has a syntax error because the control variable in the for loop cannot be of the double type. C. The program compiles but does not stop because d would always be less than 10. D. The program compiles and runs fine. Key:d In this loop, the loop initial action is d = 0, the continuation condition is d < 10, and the action-after-eachiteration is sum += sum + d. The loop body is d += 1. This code is correct in syntax. d is initially 0 and d += 0.1 adds 0.1 to d in each iteration. Eventually d will be greater than or equal to 10. So the loop will terminate. The correct answer for this question is (D) The program compiles and runs fine. # Section 5.11 Case Studies 25. What is y after the following for loop statement is executed? int y = 0; for (int i = 0; i < 10; ++i) { y += 1; } A. 9 B. 10 C. 11 D. 12 Key:b Before the loop, y is 0. The loop is executed 10 times. Each time, 1 is added to y. So, after the loop is finished, y is 10. The correct answer is (B). # Section 5.12 Keywords break and continue 26. Will the following program terminate? int balance = 10; while (true) { if (balance &lt; 9) break; balance = balance - 9; } a. Yes b. No Key:a Yes. Before the loop, balance is 10. The loop-continuation-condition is always true. In the first iteration, balance is reduced to 1. In the second iteration, the break statement is executed since (balance < 9) is now true. The correct answer for this question is A. # 27.

What is sum after the following loop terminates?

int sum = 0; int item = 0; do { item++; sum += item; if (sum &gt; 4) break; } while (item &lt; 5); a. 5 ..

b. 6 c. 7 d. 8 e. 9 Key:b sum and item are initialized to 0 before the loop. In the loop, item++ increments item by 1 and item is then added to sum. If sum > 4, the break statement exits the loop. item is initially 0, then 1, 2, 3 and sum is initially 0, and then 1, 3, and 6. When sum is 6, (sum > 4) is true, which causes the break statement to be executed. So, the correct answer is B. # 28.

What is the output after the following loop terminates?

int number = 25; int i; boolean isPrime = true; for (i = 2; i < number && isPrime; i++) { if (number % i == 0) { isPrime = false; } } System.out.println("i is " + i + " isPrime is " + isPrime); a. i is 5 isPrime is true b. i is 5 isPrime is false c. i is 6 isPrime is true d. i is 6 isPrime is false Key:d The code tests if number is prime by dividing the number with possible divisors 2, 3, 4, and so on. Initially, isPrime is set to true. Once a divisor is found (i.e., number % i == 0 is true), isPrime is set to false. The loop continuation condition now becomes false. The loop ends. If no divisor is found after the loop is finished, isPrime remains true. Since number is 25, number % i == 0 is true when i is 5. In this case, isPrime is set to false and i++ increments i by 1 in the action-after-each-iteration. So, the output is that i is 6 and isPrime is false. The correct anwer is D. # 29.

What is the output after the following loop terminates?

int number = 25; int i; boolean isPrime = true; for (i = 2; i < number; i++) { if (number % i == 0) { isPrime = false; break; } } System.out.println("i is " + i + " isPrime is " + isPrime); a. b. c.

i is 5 isPrime is true i is 5 isPrime is false i is 6 isPrime is true ..

d. i is 6 isPrime is false Key:b The code tests if number is prime by dividing the number with possible divisors 2, 3, 4, and so on. Initially, isPrime is set to true. Once a divisor is found (i.e., number % i == 0 is true), isPrime is set to false and the break statement is then executed to exit the loop. If no divisor is found after the loop is finished, isPrime remains true. Since number is 25, number % i == 0 is true when i is 5. In this case, isPrime is set to false and the loop exits. So, the output is that i is 5 and isPrime is true. The correct answer is B. # 30.

What is sum after the following loop terminates?

int sum = 0; int item = 0; do { item++; if (sum &gt;= 4) continue; sum += item; } while (item &lt; 5); a. 6 b. 7 c. 8 d. 9 e. 10 Key:a In this loop, when sum >= 4, the continue statement is executed to exit the current iteration so the next statement sum += item after the if statement will not be executed. The loop keeps adding item to sum for item 1, 2, 3, and so on. So sum is 1, 2, and 6. When sum is 6, sum >=4 is true, the continue statement is executed to skip the rest of the iteration. When the loop ends, sum is still 6. So, the correct answer is A. # 31.

Will the following program terminate?

int balance = 10; while (true) { if (balance &lt; 9) continue; balance = balance - 9; } a. Yes b. No Key:b Before the loop, balance is 10. In the loop, balance becomes 1. The loop-continuation-condition is always true. When balance < 9 is true, the continue statement is executed to skip the rest statement in the iteration. So the loop continues in an infinite loop. So, the correct answer is B. # 32.

What balance after the following code is executed?

int balance = 10; while (balance >= 1) { if (balance < 9) continue; balance = balance - 9; ..

} A. -1 B. 0 C. 1 D. 2 E. The loop does not end Key:e Before the loop, balance is 10. The loop-continuation-condition is true (10 >= 1). In the first iteration, balance is reduced to 1. Since 1 >= 1 is true, the loop body is executed. Since balance < 9 is true, the continue statement is executed to skip the rest statement in the iteration. balance continues to be 1 and the continue statement is executed to skip the rest statement in the iteration. So the loop runs infinitely. So the correct answer to this question is E. # 33.

What is the value of balance after the following code is executed?

int balance = 10; while (balance >= 1) { if (balance < 9) break; balance = balance - 9; } A. -1 B. 0 C. 1 D. 2 Key:c Before the loop, balance is 10. The loop-continuation-condition is true (10 >= 1). In the first iteration, balance is reduced to 1. Since 1 >= 1 is true, the loop body is executed. Since balance < 9 is true, the break statement is executed to exit the loop. So, balance is 1 after the loop is finished. The correct answer for this question is C. # Section 5.13 Case Study: Checking Palindromes 34. What is the number of iterations in the following loop? for (int i = 1; i < n; i++) { // iteration } a. 2*n b. n c. n - 1 d. n + 1 Key:c The loop is executed n – 1 times for i from 1 to n – 1. So, the correct answer is C. # 35. What is the number of iterations in the following loop? for (int i = 1; i <= n; i++) { // iteration } a. 2*n b. n c. n - 1 d. n + 1 ..

Key:b The loop is executed n times for i from 1 to n. So, the correct answer is B. # Section 5.14 Case Study: Displaying Prime Numbers 36. Suppose the input for number is 9. What is the output from running the following program? import java.util.Scanner; public class Test { public static void main(String[] args) { Scanner input = new Scanner(System.in); System.out.print("Enter an integer: "); int number = input.nextInt(); int i; boolean isPrime = true; for (i = 2; i < number && isPrime; i++) { if (number % i == 0) { isPrime = false; } } System.out.println("i is " + i); if (isPrime) System.out.println(number + " is prime"); else System.out.println(number + " is not prime"); } } a. i is 3 followed by 9 is prime b. i is 3 followed by 9 is not prime c. i is 4 followed by 9 is prime d. i is 4 followed by 9 is not prime Key:d The input number is 9. isPrime is initialized to true. The loop tests if number is divisible by i for i from 2, 3, and so on. When i is 3, isPrime is false. The loop continuation condition becomes false. The loop is not finished. Before the loop continuation condition is checked, i++ increments i by 1. So, output is that i is 4 and following by 9 is not prime. So, the correct answer is is executed n times for i from 1 to n. So, the correct answer is D. # 37. Analyze the following code: import java.util.Scanner; public class Test { public static void main(String[] args) { int sum = 0; for (int i = 0; i < 100000; i++) { Scanner input = new Scanner(System.in); sum += input.nextInt(); } } ..

} a. The program does not compile because the Scanner input = new Scanner(System.in); statement is inside the loop. b. The program compiles, but does not run because the Scanner input = new Scanner(System.in); statement is inside the loop. c. The program compiles and runs, but it is not efficient and unnecessary to execute the Scanner input = new Scanner(System.in); statement inside the loop. You should move the statement before the loop. d. The program compiles, but does not run because there is not prompting message for entering the input. Key:c To receive input from the keyboard, you need to create an input object from the Scanner class. You should create this object only once in the program. Placing the statement Scanner input = new Scanner(System.in) in the loop causes it to be created multiple times, which is a bad practice and could lead to potential errors. So, the correct answer is C.

Chapter 6 Methods Sections 6.2 Defining a Method 1. Suppose your method does not return any value, which of the following keywords can be used as a return type? a. void b. int c. double d. public e. None of the above Key:a See the third paragraph in this section. # 2. The signature of a method consists of . a. method name b. method name and parameter list c. return type, method name, and parameter list d. parameter list Key:b By definition, a method signature consists of method name and parameter list. # 3. All Java applications must have a method . a. public static Main(String[] args) b. public static Main(String args[]) c. public static void main(String[] args) d. public void main(String[] args) e. public static main(String[] args) Key:c Java application's starting method is the main method. # Sections 6.3 Calling a Method 4. Arguments to methods always appear within a. brackets b. parentheses c. curly braces d. quotation marks Key:b See Listing 6.1. # 6.

Does the method call in the following method cause compile errors?

public static void main(String[] args) { Math.pow(2, 4); } a. Yes b. No Key:b A value-returning method can also be invoked as a statement in Java. In this case, the caller simply ignores the return value. This is rare, but permissible if the caller is not interested in the return value. # 7. Each time a method is invoked, the system stores parameters and local variables in an area of memory, known as , which stores elements in last-in first-out fashion. a. a heap b. storage area c. a stack © 2020 Pearson Education, Inc., Hoboken, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist.

d. an array key:c See the discussion on the activation record. # Sections 6.4 void vs. Value-Returning Methods 8. Which of the following should be defined as a void method? a. Write a method that prints integers from 1 to 100. b. Write a method that returns a random integer from 1 to 100. c. Write a method that checks whether a number is from 1 to 100. d. Write a method that converts an uppercase letter to lowercase. key:a A method that does not return a value should be defined void. # 9. You should fill in the blank in the following code with

public class Test { public static void main(String[] args) { System.out.print("The grade is "); printGrade(78.5); System.out.print("The grade is "); printGrade(59.5); } public static printGrade(double score) { if (score >= 90.0) { System.out.println('A'); } else if (score >= 80.0) { System.out.println('B'); } else if (score >= 70.0) { System.out.println('C'); } else if (score >= 60.0) { System.out.println('D'); } else { System.out.println('F'); } } } a. int b. double c. boolean d. char e. void key:e void should to be used here because the method does not return any value. # 10. You should fill in the blank in the following code with

public static void main(String[] args) { System.out.print("The grade is " + getGrade(78.5)); System.out.print("\nThe grade is " + getGrade(59.5)); } public static getGrade(double score) { if (score >= 90.0) return 'A'; else if (score >= 80.0) return 'B'; else if (score >= 70.0) return 'C'; else if (score >= 60.0) return 'D'; else return 'F'; } } a. int b. double c. boolean d. char e. void key:d char should be placed here because the method returns a character. # 5.

Does the return statement in the following method cause compile errors?

public static void main(String[] args) { int max = 0; if (max != 0) System.out.println(max); else return; } a. Yes b. No Key:b See the Caution box. It is rare, but sometimes useful to have a return statement for circumventing the normal flow of control in a void method. # 11. Consider the following incomplete code. The missing method body should be

public class Test { public static void main(String[] args) { System.out.println(f(5)); } public static int f(int number) { // Missing body } } © 2020 Pearson Education, Inc., Hoboken, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist.

a. return "number"; b. System.out.println(number); c. System.out.println("number"); d. return number; Key:d The method returns and int. So D is correct. # Sections 6.5 Passing Parameters by Values 12. When you invoke a method with a parameter, the value of the argument is passed to the parameter. This is referred to as . a. method invocation b. pass by value c. pass by reference d. pass by name key:b See the third paragraph in this section. # 13. Given the following method, what is the output of the call nPrint('a', 4)? static void nPrint(String message, int n) { while (n > 0) { System.out.print(message); n--; } } a. aaaaa b. aaaa c. aaa d. invalid call Key:d Invalid call because char 'a' cannot be passed to string message # 14. Given the following method static void nPrint(String message, int n) { while (n > 0) { System.out.print(message); n--; } } What is k after invoking nPrint("A message", k)? int k = 2; nPrint("A message", k); a. 0 b. 1 c. 2 d. 3 Key:c See Listing 6.4. # Section 6.8 Overloading Methods © 2020 Pearson Education, Inc., Hoboken, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist.

15. Analyze the following code: public class Test { public static void main(String[] args) { System.out.println(xMethod(5, 500L)); } public static int xMethod(int n, long l) { System.out.println("int, long"); return n; } public static long xMethod(long n, long l) { System.out.println("long, long"); return n; } } a. The program displays int, long followed by 5. b. The program displays long, long followed by 5. c. The program runs fine but displays things other than 5. d. The program does not compile because the compiler cannot distinguish which xmethod to invoke. Key:a See Listing 6.9. # 16.

Analyze the following code:

class Test { public static void main(String[] args) { System.out.println(xmethod(5)); } public static int xmethod(int n, long t) { System.out.println("int"); return n; } public static long xmethod(long n) { System.out.println("long"); return n; } } a. The program displays int followed by 5. b. The program displays long followed by 5. c. The program runs fine but displays things other than 5. d. The program does not compile because the compiler cannot distinguish which xmethod to invoke. Key:b See Listing 6.9. # 17. Analyze the following code. public class Test { public static void main(String[] args) { System.out.println(max(1, 2)); } © 2020 Pearson Education, Inc., Hoboken, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist.

public static double max(int num1, double num2) { System.out.println("max(int, double) is invoked"); if (num1 > num2) return num1; else return num2; } public static double max(double num1, int num2) { System.out.println("max(double, int) is invoked"); if (num1 > num2) return num1; else return num2; } } a. The program cannot compile because you cannot have the print statement in a non-void method. b. The program cannot compile because the compiler cannot determine which max method should be invoked. c. The program runs and prints 2 followed by "max(int, double)" is invoked. d. The program runs and prints 2 followed by "max(double, int)" is invoked. e. The program runs and prints "max(int, double) is invoked" followed by 2. Key:b This is known as ambiguous method invocation. See the last Note box in this section. # 18. Analyze the following code. public class Test { public static void main(String[] args) { System.out.println(m(2)); } public static int m(int num) { return num; } public static void m(int num) { System.out.println(num); } } a. The program has a compile error because the two methods m have the same signature. b. The program has a compile error because the second m method is defined, but not invoked in the main method. c. The program runs and prints 2 once. d. The program runs and prints 2 twice. Key:a You cannot overload the methods based on the type returned. See the first Note box in this section. # Section 6.9 The Scope of Variables 19. A variable defined inside a method is referred to as a. a global variable b. a method variable c. a block variable

d. a local variable key:d See the first paragraph. # 20. What is k after the following block executes? { int k = 2; nPrint("A message", k); } System.out.println(k); a. 0 b. 1 c. 2 d. k is not defined outside the block. So, the program has a compile error Key:d k is defined inside the block. Outside the block, k is not defined. # Section 6.10 Case Study: Generating Random Characters 21. (int)(Math.random() * (65535 + 1)) returns a random number a. between 1 and 65536 b. between 1 and 65535 c. between 0 and 65535 d. between 0 and 65536 key:c See the second paragraph in this section. # 22. (int)('a' + Math.random() * ('z' - 'a' + 1)) returns a random number a. between 0 and (int)'z' b. between (int)'a' and (int)'z' c. between 'a' and 'z' d. between 'a' and 'y' key:b See LiveExample 6.10. # 23. (char)('a' + Math.random() * ('z' - 'a' + 1)) returns a random character a. between 'a' and 'z' b. between 'a' and 'y' c. between 'b' and 'z' d. between 'b' and 'y' key:a See LiveExample 6.10.

# 24. Which of the following is the best for generating random integer 0 or 1? a. (int)Math.random() b. (int)Math.random() + 1 c. (int)(Math.random() + 0.5) d. (int)(Math.random() + 0.2) e. (int)(Math.random() + 0.8) key:c 50% of (Math.random() + 0.5) is <= 1 and 50% of (Math.random() + 0.5) is > 1. So, C is the correct. # Section 6.11 Method Abstraction and Stepwise Refinement 25. The client can use a method without knowing how it is implemented. The details of the implementation are © 2020 Pearson Education, Inc., Hoboken, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist.

encapsulated in the method and hidden from the client who invokes the method. This is known as a. information hiding b. encapsulation c. method hiding d. simplifying method key:ab See the first paragraph.

# 26. is to implement one method in the structure chart at a time from the top to the bottom. a. Bottom-up approach b. Top-down approach c. Bottom-up and top-down approach d. Stepwise refinement key:b See Section 6.11.2. # 27. is a simple but incomplete version of a method. a. A stub b. A main method c. A non-main method d. A method developed using top-down approach key:a See Section 6.11.2.

Chapter 7 Single-Dimensional Arrays Section 7.2 Array Basics 3. Once an array is created, its size a. can be changed b. is fixed c. is not determined Key:b See the Key Point.

# Section 7.2.1 Declaring Array Variables 3. Which of the following are correct to declare an array of int values? a. int[] a; b. int a[]; c. int a; d. double[] a; Key:ab See the first paragraph. # Section 7.2.2 Creating Arrays 3. Which of the following are incorrect? a. int[] a = new int[2]; b. int a[] = new int[2]; c. int[] a = new int(2); d. int a = new int[2]; e. int a() = new int[2]; Key:cde See Sections 7.2.1 and 7.2.2. # 4. If you declare an array double[] list = new double[5], the highest index in array list is a. 0 b. 1 c. 2 d. 3 e. 4 Key:e See Figure 7.1. # Section 7.2.3 Array Size and Default Values 5. How many elements are in array double[] list = new double[5]? a. 4 b. 5 c. 6 d. 0 Key:b See Figure 7.1. # 8.

Analyze the following code.

public class Test { public static void main(String[] args) { © 2020 Pearson Education, Inc., Hoboken, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist.

int[] x = new int[3]; System.out.println("x[0] is " + x[0]); } } a. The program has a compile error because the size of the array wasn't specified when declaring the array. b. The program has a runtime error because the array elements are not initialized. c. The program runs fine and displays x[0] is 0. d. The program has a runtime error because the array element x[0] is not defined. Key:c The default value for an int array element is 0. # Section 7.2.4 Accessing Array Elements 6. What is the correct term for numbers[99]? a. index b. index variable c. indexed variable d. array variable e. array Key:c See Section 7.2.4. # 1. What is the representation of the third element in an array called a? a. a[2] b. a(2) c. a[3] d. a(3) Key:a See Section 7.2.4. # 7. Suppose int i = 5, which of the following can be used as an index for array double[] t = new double[100]? a. i b. (int)(Math.random() * 100)) c. i + 10 d. i + 6.5 e. Math.random() * 100 Key:abc The array t has 100 elements and its index is an integer from 0 to 99. So, A, B, C are all correct. D and E are double values, not integers. # Section 7.2.5 Array Initializers 2. If you declare an array double[] list = {3.4, 2.0, 3.5, 5.5}, list[1] is a. 3.4 b. 2.0 c. 3.5 d. 5.5 e. undefined Key:b See Section 7.2.5. # 9. a. b. c. d.

Which of the following statements are valid? int i = new int(30); double d[] = new double[30]; int[] i = {3, 4, 3, 2}; char[] c = new char();

e. char[] c = new char[4]{'a', 'b', 'c', 'd'}; Key:bc e would be corrected if it is char[] c = new char[]{'a', 'b', 'c', 'd'}; # 10. How can you initialize an array of two characters to 'a' and 'b'? a. char[] charArray = new char[2]; charArray = {'a', 'b'}; b. char[2] charArray = {'a', 'b'}; c. char[] charArray = {'a', 'b'}; d. char[] charArray = new char[2]; charArray[0] = 'a'; charArray[1] = 'b'; Key:cd See Section 7.2.5. # 12. Assume int[] t = {1, 2, 3, 4}. What is t.length? a. 0 b. 3 c. 4 d. 5 Key:c See Section 7.2.5. # Section 7.2.6 Processing Arrays 13. What is the output of the following code? double[] myList = {1, 5, 5, 5, 5, 1}; double max = myList[0]; int indexOfMax = 0; for (int i = 1; i < myList.length; i++) { if (myList[i] > max) { max = myList[i]; indexOfMax = i; } } System.out.println(indexOfMax); a. 0 b. 1 c. 2 d. 3 e. 4 Key:b The code displays the index of the first max value in the array. # 14. Analyze the following code: public class Test { public static void main(String[] args) { int[] x = new int[5]; int i; for (i = 0; i < x.length; i++) x[i] = i; System.out.println(x[i]); } } a. The program displays 0 1 2 3 4. b. The program displays 4. © 2020 Pearson Education, Inc., Hoboken, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist.

c. The program has a runtime error because the last statement in the main method causes ArrayIndexOutOfBoundsException. d. The program has a compile error because i is not defined in the last statement in the main method. Key:c After the for loop i is 5. x[5] is out of bounds. # 16. What is the output of the following code? int[] myList = {1, 2, 3, 4, 5, 6}; for (int i = myList.length - 2; i >= 0; i--) { myList[i + 1] = myList[i]; } for (int e: myList) System.out.print(e + " "); a. 123456 b. 6 1 2 3 4 5 c. 623451 d. 1 1 2 3 4 5 e. 234561 Key:d See Shifting elements in Item #8. # Section 7.2.7 Foreach Loops 15. Analyze the following code: public class Test { public static void main(String[] args) { double[] x = {2.5, 3, 4}; for (double value: x) System.out.print(value + " "); } } a. The program displays 2.5, 3, 4 b. The program displays 2.5 3 4 c. The program displays 2.5 3.0 4.0 d. The program displays 2.5, 3.0 4.0 e. The program has a syntax error because value is undefined. Key:c See the first paragraph. # Section 7.3 Case Study: Analyzing Numbers 17. What is output of the following code: public class Test { public static void main(String[] args) { int[] x = {120, 200, 016}; for (int i = 0; i < x.length; i++) System.out.print(x[i] + " "); } } a. 120 200 16

b. 120 200 14 c. 120 200 20 d. 016 is a compile error. It should be written as 16. Key:b 016 is an octal number. The prefix 0 indicates that a number is in octal. # Section 7.4 Case Study: Deck of Cards 18. What is output of the following code: public class Test { public static void main(String[] args) { int list[] = {1, 2, 3, 4, 5, 6}; for (int i = 1; i < list.length; i++) list[i] = list[i - 1]; for (int i = 0; i < list.length; i++) System.out.print(list[i] + " "); } } a. 123456 b. 234566 c. 234561 d. 111111 Key:d The first element is copied to the second, the second is then copied to the third, and so on. # Section 7.5 Copying Arrays 20. In the following code, what is the output for list2? public class Test { public static void main(String[] args) { int[] list1 = {1, 2, 3}; int[] list2 = {1, 2, 3}; list2 = list1; list1[0] = 0; list1[1] = 1; list2[2] = 2; for (int i = 0; i < list2.length; i++) System.out.print(list2[i] + " "); } } a. 1 2 3 b. 1 1 1 c. 0 1 2 d. 0 1 3 Key:c list2 = list1 makes list2 point to the same array as list1. See Figure 7.4. # 22. Analyze the following code: public class Test { public static void main(String[] args) { int[] x = {1, 2, 3, 4}; int[] y = x; © 2020 Pearson Education, Inc., Hoboken, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist.

x = new int[2]; for (int i = 0; i < y.length; i++) System.out.print(y[i] + " "); } } a. The program displays 1 2 3 4 b. The program displays 0 0 c. The program displays 0 0 3 4 d. The program displays 0 0 0 0 Key:a y is {1, 2, 3, 4} and x is {0, 0}. # 24. Analyze the following code: public class Test { public static void main(String[] args) { final int[] x = {1, 2, 3, 4}; int[] y = x; x = new int[2]; for (int i = 0; i < y.length; i++) System.out.print(y[i] + " "); } } a. The program displays 1 2 3 4. b. The program displays 0 0. c. The program has a compile error on the statement x = new int[2], because x is final and cannot be changed. d. The elements in the array x cannot be changed, because x is final. Key:c The value stored in x is final, but the values in the array are not final. x is a constant reference variable that points to an array with four elements Because it is a constant, you cannot create a new reference variable x that points to a different array, but you can change the value of the elements in the array, e.g. x[1] could be changed to 10 instead of 2. # 25. Analyze the following code. int[] list = new int[5]; list = new int[6]; a. The code has compile errors because the variable list cannot be changed once it is assigned. b. The code has runtime errors because the variable list cannot be changed once it is assigned. c. The code can compile and run fine. The second line assigns a new array to list. d. The code has compile errors because you cannot assign a different size array to list. Key:c See Figure 7.4. # 26. Analyze the following code: public class Test { public static void main(String[] args) { int[] a = new int[4]; a[1] = 1;

a = new int[2]; System.out.println("a[1] is " + a[1]); } } a. The program has a compile error because new int[2] is assigned to a. b. The program has a runtime error because a[1] is not initialized. c. The program displays a[1] is 0. d. The program displays a[1] is 1. Key:c After executing the statement a = new int[2], a refers to int[2]. The default value for a[0] and a[1] is 0. # 27. The method copies the sourceArray to the targetArray. a. System.copyArrays(sourceArray, 0, targetArray, 0, sourceArray.length); b. System.copyarrays(sourceArray, 0, targetArray, 0, sourceArray.length); c. System.arrayCopy(sourceArray, 0, targetArray, 0, sourceArray.length); d. System.arraycopy(sourceArray, 0, targetArray, 0, sourceArray.length); Key:d See the discussion on the arraycopy method in this section. # 21. In the following code, what is the output for list1? public class Test { public static void main(String[] args) { int[] list1 = {1, 2, 3}; int[] list2 = {1, 2, 3}; list2 = list1; list1[0] = 0; list1[1] = 1; list2[2] = 2; for (int i = 0; i < list1.length; i++) System.out.print(list1[i] + " "); } } a. 1 2 3 b. 1 1 1 c. 0 1 2 d. 0 1 3 Key:c list2 = list1 makes list2 point to the same array as list1. See Figure 7.4. # 23. Analyze the following code: public class Test { public static void main(String[] args) { int[] x = {1, 2, 3, 4}; int[] y = x; x = new int[2]; for (int i = 0; i < x.length; i++) System.out.print(x[i] + " "); } } a. b.

The program displays 1 2 3 4 The program displays 0 0

c. The program displays 0 0 3 4 d. The program displays 0 0 0 0 Key:b y is {1, 2, 3, 4} and x is {0, 0} # Section 7.6 Passing Arrays to Methods 29. Show the output of the following code: public class Test { public static void main(String[] args) { int[] x = {1, 2, 3, 4, 5}; increase(x); int[] y = {1, 2, 3, 4, 5}; increase(y[0]); System.out.println(x[0] + " " + y[0]); } public static void increase(int[] x) { for (int i = 0; i < x.length; i++) x[i]++; } public static void increase(int y) { y++; } } a. 00 b. 11 c. 22 d. 21 e. 12 Key:d Invoking increase(x) passes the reference of the array to the method. Invoking increase(y[0]) passes the value 1 to the method. The value y[0] outside the method is not changed. # 31.

Analyze the following code:

public class Test { public static void main(String[] args) { int[] oldList = {1, 2, 3, 4, 5}; reverse(oldList); for (int i = 0; i < oldList.length; i++) System.out.print(oldList[i] + " "); } public static void reverse(int[] list) { int[] newList = new int[list.length]; for (int i = 0; i < list.length; i++) newList[i] = list[list.length - 1 - i]; list = newList;

} } a. The program displays 1 2 3 4 5. b. The program displays 1 2 3 4 5 and then raises an ArrayIndexOutOfBoundsException. c. The program displays 5 4 3 2 1. d. The program displays 5 4 3 2 1 and then raises an ArrayIndexOutOfBoundsException. Key:a The contents of the array oldList have not been changed as result of invoking the reverse method. # 32. Analyze the following code: public class Test1 { public static void main(String[] args) { xMethod(new double[]{3, 3}); xMethod(new double[5]); xMethod(new double[3]{1, 2, 3}); } public static void xMethod(double[] a) { System.out.println(a.length); } } a. The program has a compile error because xMethod(new double[]{3, 3}) is incorrect. b. The program has a compile error because xMethod(new double[5]) is incorrect. c. The program has a compile error because xMethod(new double[3]{1, 2, 3}) is incorrect. d. The program has a runtime error because a is null. Key:c new double[3]{1, 2, 3} should be replaced by new double[]{1, 2, 3}) (anonymous array). # 11.

What would be the result of attempting to compile and run the following code?

public class Test { public static void main(String[] args) { double[] x = new double[]{1, 2, 3}; System.out.println("Value is " + x[1]); } } a. The program has a compile error because the syntax new double[]{1, 2, 3} is wrong and it should be replaced by {1, 2, 3}. b. The program has a compile error because the syntax new double[]{1, 2, 3} is wrong and it should be replaced by new double[3]{1, 2, 3}; c. The program has a compile error because the syntax new double[]{1, 2, 3} is wrong and it should be replaced by new double[]{1.0, 2.0, 3.0}; d. The program compiles and runs fine and the output "Value is 1.0" is printed. e. The program compiles and runs fine and the output "Value is 2.0" is printed. Key:e new double[]{1, 2, 3} is correct. double[] x = new double[]{1, 2, 3} is equivalent to double[] x = {1, 2, 3}; # 30.

Do the following two programs produce the same result?

Program I: public class Test { public static void main(String[] args) {

int[] list = {1, 2, 3, 4, 5}; for (int i = 0; i < list.length; i++) System.out.print(list[i] + " "); } } Program II: public class Test { public static void main(String[] args) { int[] oldList = {1, 2, 3, 4, 5}; reverse(oldList); for (int i = 0; i < oldList.length; i++) System.out.print(oldList[i] + " "); } public static void reverse(int[] list) { int[] newList = new int[list.length]; for (int i = 0; i < list.length; i++) newList[i] = list[list.length - 1 - i]; list = newList; } } a. Yes b. No Key:a In Program II, the reference of newList is assigned to list. This does not change the reference for list after calling reverse. So, list is not changed after the call. # 28. When you pass an array to a method, the method receives a. a copy of the array b. a copy of the first element c. the reference of the array d. the length of the array Key:c See the code animation for TestArrayArguments.

# 33. The JVM stores the array in an area of memory, called , which is used for dynamic memory allocation where blocks of memory are allocated and freed in an arbitrary order. a. stack b. heap c. memory block d. dynamic memory key:b See the Note after Figure 5.7. # 19. Which of the following is correct? a. String[] list = new String{"red", "yellow", "green"}; b. String[] list = new String[]{"red", "yellow", "green"}; c. String[] list = {"red", "yellow", "green"}; d. String list = {"red", "yellow", "green"}; e. String list = new String{"red", "yellow", "green"}; Key:bc See the note before CodeAnimation TestArrayArguments.

# Section 7.7 Returning an Array from a Method 34. When you return an array from a method, the method returns a. a copy of the array b. a copy of the first element c. the reference of the array d. the length of the array Key:c See the Key Point of this section.

# 35. Suppose a method p has the following heading: public static int[] p() What return statement may be used in p()? a. return 1; b. return {1, 2, 3}; c. return int[]{1, 2, 3}; d. return new int[]{1, 2, 3}; Key:d The correct syntax to create an array is new int[]{1, 2, 3}. # 36. The reverse method is defined in the textbook. What is list1 after executing the following statements? int[] list1 = {1, 2, 3, 4, 5, 6}; list1 = reverse(list1); a. list1 is 1 2 3 4 5 6 b. list1 is 6 5 4 3 2 1 c. list1 is 0 0 0 0 0 0 d. list1 is 6 6 6 6 6 6 key:b The reverse method in this section returns a new array that is the reversal of the source. # 37. The reverse method is defined in this section. What is list1 after executing the following statements? int[] list1 = {1, 2, 3, 4, 5, 6}; int[] list2 = reverse(list1); a. list1 is 1 2 3 4 5 6 b. list1 is 6 5 4 3 2 1 c. list1 is 0 0 0 0 0 0 d. list1 is 6 6 6 6 6 6 key:a See the reverse method in this section. # Section 7.9 Variable-Length Argument Lists 38. Which of the following declarations are correct? a. public static void print(String... strings, double... numbers) b. public static void print(double... numbers, String name) c. public static double... print(double d1, double d2)

d. public static void print(double... numbers) e. public static void print(int n, double... numbers) Key:de Only one variable-length parameter may be specified in a method and this parameter must be the last parameter. The method return type cannot be a variable-length parameter. # 39. Which of the following statements are correct to invoke the printMax method in Listing 7.5 in the textbook? a. printMax(1, 2, 2, 1, 4); b. printMax(new double[]{1, 2, 3}); c. printMax(1.0, 2.0, 2.0, 1.0, 4.0); d. printMax(new int[]{1, 2, 3}); Key:abc The last one printMax(new int[]{1, 2, 3}); is incorrect, because the array must of the double[] type. # Section 7.10 Searching Arrays 40. For the binarySearch method in Section 7.10.2, what is low and high after the first iteration of the while loop when invoking binarySearch(new int[]{1, 4, 6, 8, 10, 15, 20}, 11)? a. low is 0 and high is 6 b. low is 5 and high is 5 c. low is 3 and high is 6 d. low is 4 and high is 6 e. low is 6 and high is 5 key:d See Listing 7.7. # 41. If a key is not in the list, the binarySearch method returns a. insertion point b. insertion point - 1 c. -(insertion point + 1) d. -insertion point key:c See Listing 7.7.

# Section 7.11 Sorting Arrays 42. Use the selectionSort method presented in this section to answer this question. Assume list is {3.1, 3.1, 2.5, 6.4, 2.1}, what is the content of list after the first iteration of the outer loop in the method? a. 3.1, 3.1, 2.5, 6.4, 2.1 b. 2.5, 3.1, 3.1, 6.4, 2.1 c. 2.1, 2.5, 3.1, 3.1, 6.4 d. 3.1, 3.1, 2.5, 2.1, 6.4 e. 2.1, 3.1, 2.5, 6.4, 3.1 Key:e See Listing 7.8. # 43. Use the selectionSort method presented in this section to answer this question. What is list1 after executing the following statements? double[] list1 = {3.1, 3.1, 2.5, 6.4}; selectionSort(list1); a. b.

list1 is 3.1, 3.1, 2.5, 6.4 list1 is 2.5, 3.1, 3.1, 6.4

c. list1 is 6.4, 3.1, 3.1, 2.5 d. list1 is 3.1, 2.5, 3.1, 6.4 Key:b See Listing 7.7. # Section 7.12 The Arrays Class 44. The method sorts the array scores of the double[] type. a. java.util.Arrays(scores) b. java.util.Arrays.sorts(scores) c. java.util.Arrays.sort(scores) d. java.util.Arrays.sortArray(scores) Key:c See the second paragraph in this section. # 45. Assume int[] scores = {1, 20, 30, 40, 50}, what value does java.util.Arrays.binarySearch(scores, 30) return? a. 0 b. -1 c. 1 d. 2 e. -2 Key:d See the fourth paragraph in this section. # 46. Assume int[] scores = {1, 20, 30, 40, 50}, what value does java.util.Arrays.binarySearch(scores, 3) return? a. 0 b. -1 c. 1 d. 2 e. -2 Key:e The binarySearch method returns the index of the search key if it is contained in the list. Otherwise, it returns insertionPoint - 1. The insertion point is the point at which the key would be inserted into the list. In this case the insertion point is 1. Note that the array index starts from 0. # 47. Assume int[] scores = {1, 20, 30, 40, 50}, what is the output of System.out.println(java.util.Arrays.toString(scores))? a. {1, 20, 30, 40, 50} b. [1, 20, 30, 40, 50] c. {1 20 30 40 50} d. [1 20 30 40 50] Key:b See the toString method in this section. # Section 7.13 Command-Line Arguments 48. How can you get the word "abc" in the main method from the following call? java Test "+" 3 "abc" 2 a. args[0] b. args[1] c. args[2] d. args[3] Key:c See Section 7.13.2. #

49. Given the following program: public class Test { public static void main(String[] args) { for (int i = 0; i < args.length; i++) { System.out.print(args[i] + " "); } } } What is the output, if you run the program using java Test 1 2 3 a. 3 b. 1 c. 123 d. 1 2 Key:c See Section 7.13.2. # 50. Which code fragment would correctly identify the number of arguments passed via the command line to a Java application, excluding the name of the class that is being invoked? a. int count = args.length; b. int count = args.length - 1; c. int count = 0; while (args[count] != null) count ++; d. int count=0; while (!(args[count].equals(""))) count ++; Key:a See LiveExample 7.9. # 51. Which correctly creates an array of five empty Strings? a. String[] a = new String [5]; b. String[] a = {"", "", "", "", ""}; c. String[5] a; d. String[ ] a = new String [5]; for (int i = 0; i &lt; 5; a[i++] = null); Key:b See LiveExample 7.9. # 52. Analyze the following code: public class Test { public static void main(String argv[]) { System.out.println("argv.length is " + argv.length); } } a. The program has a compile error because String argv[] is wrong and it should be replaced by String[] args. b. The program has a compile error because String argv[] is wrong and it should be replaced by String args[]. c. If you run this program without passing any arguments, the program would have a runtime error because argv is null. d. If you run this program without passing any arguments, the program would display argv.length is 0. Key:d The parameter for the main method is an array of String. The declaration String argv[] is correct. When you run the program without passing arguments, argv is new String[0]. Thus, argv.length is 0. See the NOTE box in the section, "Passing Arguments to Java Programs."

# 53. Which of the following is the correct header of the main method? a. public static void main(String[] args) b. public static void main(String args[]) c. public static void main(String[] x) d. public static void main(String x[]) e. static void main(String[] args) Key:abcd e is incorrect because the main method must be public.

Chapter 8 Multidimensional Arrays Section 8.2 Two-Dimensional Array Basics Section 8.2.1 Declaring Variables of Two-Dimensional Arrays and Creating Two-Dimensional Arrays 1. Which of the following statements are correct? a. char[][] charArray = {'a', 'b'}; b. char[2][2] charArray = {{'a', 'b'}, {'c', 'd'}}; c. char[2][] charArray = {{'a', 'b'}, {'c', 'd'}}; d. char[][] charArray = {{'a', 'b'}, {'c', 'd'}}; Key:d See Section 8.2.1. # 3. What is the index variable for the element at the first row and first column in array a? a. a[0][0] b. a[1][1] c. a[0][1] d. a[1][0] Key:a Array index starts from 0. # 4.

When you create an array using the following statement, the element values are automatically initialized to 0.

int[][] matrix = new int[5][5]; a. True b. False Key:a For a number array, the default value is 0. # Section 8.2.2 Obtaining the Lengths of Two-Dimensional Arrays 2. Assume double[][] x = new double[4][5], what are x.length and x[2].length? a. 4 and 4 b. 4 and 5 c. 5 and 4 d. 5 and 5 Key:b See Section 8.2.2. # 5. How many elements are in array matrix (int[][] matrix = new int[5][5])? a. 14 b. 20 c. 25 d. 30 Key:c It is a square matrix 5 by 5. # 7. a. b. c. d. e.

Assume int[][] x = {{1, 2}, {3, 4}, {5, 6}}, what are x.length are x[0].length? 2 and 1 2 and 2 3 and 2 2 and 3 3 and 3 ..

Key:c x.length is the number of the rows. x[0].length is the number of the elements in the first row. # Section 8.2.3 Ragged Arrays 6. Analyze the following code: public class Test { public static void main(String[] args) { boolean[][] x = new boolean[3][]; x[0] = new boolean[1]; x[1] = new boolean[2]; x[2] = new boolean[3]; System.out.println("x[2][2] is " + x[2][2]); } } a. The program has a compile error because new boolean[3][] is wrong. b. The program has a runtime error because x[2][2] is null. c. The program runs and displays x[2][2] is null. d. The program runs and displays x[2][2] is true. e. The program runs and displays x[2][2] is false. Key:e x is a ragged array. (See the section on Ragged Array) x[2] has three elements with default value false. # 8. Assume int[][] x = {{1, 2}, {3, 4, 5}, {5, 6, 5, 9}}, what are x[0].length, x[1].length, and x[2].length? a. 2, 3, and 3 b. 2, 3, and 4 c. 3, 3, and 3 d. 3, 3, and 4 e. 2, 2, and 2 Key:b x[0].length, x[1].length, and x[2].length are the number of the elements in the first, second, and third rows. # Section 8.3 Processing Two-Dimensional Arrays 12. What is the output of the following code? public class Test { public static void main(String[] args) { int[][] matrix = {{1, 2, 3, 4}, {4, 5, 6, 7}, {8, 9, 10, 11}, {12, 13, 14, 15}}; for (int i = 0; i < 4; i++) System.out.print(matrix[i][1] + " "); } } a. 1234 b. 4567 c. 1 3 8 12 d. 2 5 9 13 e. 3 6 10 14 Key:d The code displays the second column in matrix. ..

# 9.

What is the output of the following program?

public class Test { public static void main(String[] args) { int[][] values = {{3, 4, 5, 1}, {33, 6, 1, 2}}; int v = values[0][0]; for (int row = 0; row < values.length; row++) for (int column = 0; column < values[row].length; column++) if (v < values[row][column]) v = values[row][column]; System.out.print(v); } } a. 1 b. 3 c. 5 d. 6 e. 33 Key:e The code finds the largest element in the values array. # 11.

What is the output of the following program?

public class Test { public static void main(String[] args) { int[][] values = {{3, 4, 5, 1 }, {33, 6, 1, 2}}; for (int row = 0; row < values.length; row++) { java.util.Arrays.sort(values[row]); for (int column = 0; column < values[row].length; column++) System.out.print(values[row][column] + " "); System.out.println(); } } } a. The program prints two rows 3 4 5 1 followed by 33 6 1 2 b. The program prints on row 3 4 5 1 33 6 1 2 c. The program prints two rows 3 4 5 1 followed by 2 1 6 33 d. The program prints two rows 1 3 4 5 followed by 1 2 6 33 e. The program prints one row 1 3 4 5 1 2 6 33 Key:d The code sorts each row. # 13. What is the output of the following code? public class Test5 { public static void main(String[] args) { int[][] matrix = {{1, 2, 3, 4}, ..

{4, 5, 6, 7}, {8, 9, 10, 11}, {12, 13, 14, 15}}; for (int i = 0; i < 4; i++) System.out.print(matrix[1][i] + " "); } } a. 1 2 3 4 b. 4 5 6 7 c. 1 3 8 12 d. 2 5 9 13 e. 3 6 10 14 Key:b The code displays the second row. # 10.

What is the output of the following program?

public class Test { public static void main(String[] args) { int[][] values = {{3, 4, 5, 1}, {33, 6, 1, 2}}; int v = values[0][0]; for (int[] list : values) for (int element : list) if (v > element) v = element; System.out.print(v); } } a. 1 b. 3 c. 5 d. 6 e. 33 Key:a The code finds the smallest element in the values array. # Section 8.4 Passing Two-Dimensional Arrays to Methods 14. Suppose a method p has the following heading. What return statement may be used in p()? public static int[][] p() a. return 1; b. return {1, 2, 3}; c. return int[]{1, 2, 3}; d. return new int[]{1, 2, 3}; e. return new int[][]{{1, 2, 3}, {2, 4, 5}}; Key:e The return type is int[][]. new int[][]{{1, 2, 3}, {2, 4, 5}} creates an array of the int[][] type. # 15. ..

What is the output of the following program?

public class Test { public static void main(String[] args) { int[][] values = {{3, 4, 5, 1}, {33, 6, 1, 2}}; for (int row = 0; row < values.length; row++) { System.out.print(m(values[row]) + " "); } } public static int m(int[] list) { int v = list[0]; for (int i = 1; i < list.length; i++) if (v < list[i]) v = list[i]; return v; } } a. 3 33 b. 11 c. 56 d. 5 33 e. 33 5 Key:d The method m returns the largest element in a one-dimensional array. # Section 8.8 Multidimensional Arrays 16. Assume double[][][] x = new double[4][5][6], what are x.length, x[2].length, and x[0][0].length? a. 4, 5, and 6 b. 6, 5, and 4 c. 5, 5, and 5 d. 4, 5, and 4 Key:a See the first part in this section. # 18. What is the output of the following code? public class Test { public static void main(String[] args) { int[][][] data = {{{1, 2}, {3, 4}}, {{5, 6}, {7, 8}}}; System.out.print(data[1][0][0]); } } a. 1 b. 2 c. 4 d. 5 e. 6 Key:d See the first part in this section. # 19. What is the output of the following code? ..

public class Test { public static void main(String[] args) { int[][][] data = {{{1, 2}, {3, 4}}, {{5, 6}, {7, 8}}}; System.out.print(ttt(data[0])); } public static int ttt(int[][] m) { int v = m[0][0]; for (int i = 0; i < m.length; i++) for (int j = 0; j < m[i].length; j++) if (v < m[i][j]) v = m[i][j]; return v; } } a. 1 b. 2 c. 4 d. 5 e. 6 Key:c The ttt method returns the largest element in a tw-dimensional array. data[0] is {{1, 2}, {3, 4}}. # 17. Which of the following statements are correct? a. char[][][] charArray = new char[2][2][]; b. char[2][2][] charArray = {'a', 'b'}; c. char[][][] charArray = {{'a', 'b'}, {'c', 'd'}, {'e', 'f'}}; d. char[][][] charArray = {{{'a', 'b'}, {'c', 'd'}, {'e', 'f'}}}; Key:ad In A, a three-dimensionaly array is created with the last dimensional undetermined. In D, a three dimensional array is created. The charArray.length is 1, charArray[0].length is 1, and charArray[0] contains a two-dimensional array.

Chapter 9 Objects and Classes Section 9.2 Defining Classes for Objects 1. represents an entity in the real world that can be distinctly identified. a. A class b. An object c. A method d. A data field Key:b See the first part of this section. # 2. is a template that defines objects of the same type. a. A class b. An object c. A method d. A data field Key:a See the first part of this section. # 3. An object is an instance of a a. program b. class c. method d. data Key:b See the first part of this section. # 4. The keyword a. public b. private c. class d. All of the above. Key:c See Figure 9.3.

is required to declare a class.

# Section 9.3 Example: Defining Classes and Creating Objects 16. If TestCircle.java in Listing 9.1 is compiled successfully, a. TestCircle.class is created. b. Circle.class is created. c. TestCircle.class and Circle.class are created. d. No class files are created. Key:c See Figure 9.5. # Section 9.4 Constructing Objects Using Constructors 5. is invoked to create an object. a. A constructor b. The main method c. A method with a return type d. A method with the void return type Key:a See the Key Point. # ..

7. Which of the following statements are true? a. Multiple constructors can be defined in a class. b. Constructors do not have a return type, not even void. c. Constructors must have the same name as the class itself. d. Constructors are invoked using the new operator when an object is created. Key:abcd Read this short section. # 9.

Analyze the following code.

class TempClass { int i; public void TempClass(int j) { int i = j; } } public class C { public static void main(String[] args) { TempClass temp = new TempClass(2); } } a. The program has a compile error because TempClass does not have a default constructor. b. The program has a compile error because TempClass does not have a constructor with an int argument. c. The program compiles fine, but it does not run because class C is not public. d. The program compiles and runs fine. Key:b The program would be fine if the void keyword is removed from public void TempClass(int j). # 6. Which of the following statements are true? a. A default constructor is provided automatically if no constructors are explicitly declared in the class. b. At least one constructor must always be defined explicitly. c. Every class has a default constructor. d. The default constructor is a no-arg constructor. Key:ad See this short section. # 8.

Analyze the following code:

public class Test { public static void main(String[] args) { A a = new A(); a.print(); } } class A { String s; A(String s) { this.s = s; } void print() { ..

System.out.println(s); } } a. The program has a compile error because class A is not a public class. b. The program has a compile error because class A does not have a default constructor. c. The program compiles and runs fine and prints nothing. d. The program would compile and run if you change A a = new A() to A a = new A("5"). Key:bd Class A does not have a no-arg constructor, so, new A() causes a compile error. If new A() is changed to new A("5"), the program will compile fine. # Section 9.5 Accessing Objects via Reference Variables 10. Given the declaration Circle x = new Circle(), which of the following statement is most accurate. a. x contains an int value. b. x contains an object of the Circle type. c. x contains a reference to a Circle object. d. You can assign an int value to x. Key:c x is a reference variable that can reference a Circle object or null if it does not reference any object. # 17. Which of the following statements are correct? a. A reference variable is an object. b. A reference variable references to an object. c. A data field in a class must be of a primitive type. d. A data field in a class can be of an object type. Key:bd (a) is wrong because a reference variable is not an object, it is a reference that points to an object. (c) is incorrect because a class may have a data field of an object type such as String. # Section 9.5.1 Accessing an Object's Data and Methods 15. Analyze the following code. public class Test { int x; public Test(String t) { System.out.println("Test"); } public static void main(String[] args) { Test test = new Test(); System.out.println(test.x); } } a. The program has a compile error because System.out.println method cannot be invoked from the constructor. b. The program has a compile error because x has not been initialized. c. The program has a compile error because you cannot create an object from the class that defines the object. d. The program has a compile error because Test does not have a default constructor. Key:d Note that a default no-arg constructor is provided only if no constructors are explicitly defined in the class. In this case, a constructor Test(String t) is already defined. So, there is no default no-arg constructor in the Test class. # Section 9.5.2 Reference Data Fields and the null Value 11. Analyze the following code. ..

public class Test { int x; public Test(String t) { System.out.println("Test"); } public static void main(String[] args) { Test test = null; System.out.println(test.x); } } a. The program has a compile error because test is not initialized. b. The program has a compile error because x has not been initialized. c. The program has a compile error because you cannot create an object from the class that defines the object. d. The program has a compile error because Test does not have a default constructor. e. The program has a runtime NullPointerException because test is null while executing test.x. Key:e test.x will raise NullPointerException, because test is null. # 12. The default value for data field of a boolean type, numeric type, object type is a. true, 1, Null b. false, 0, null c. true, 0, null d. true, 1, null e. false, 1, null Key:b See the second and third paragraph.

, respectively.

# 13. Which of the following statements are true? a. Local variables do not have default values. b. Data fields have default values. c. A variable of a primitive type holds a value of the primitive type. d. A variable of a reference type holds a reference to where an object is stored in the memory. e. You may assign an int value to a reference variable. Key:abcd See the second and third paragraph. # Section 9.5.3 Differences between Variables of Primitive Types and Reference Types 14. Analyze the following code: public class Test { public static void main(String[] args) { double radius; final double PI = 3.15169; double area = radius * radius * PI; System.out.println("Area is " + area); } } a. The program has compile errors because the variable radius is not initialized. b. The program has a compile error because a constant PI is defined inside a method. c. The program has no compile errors but will get a runtime error because radius is not initialized. d. The program compiles and runs fine. ..

Key:a radius is a local variable. It is used in radius * radius * PI, but not initialized. # Section 9.6 Using Classes From the Java Library 18. Which of the following creates an object of the Date class: A: public class Test { public Test() { new java.util.Date(); } } B: public class Test { public Test() { java.util.Date date = new java.util.Date(); } } a. A. b. B. c. Neither d. Both A and B Key:d Both (A) and (B) are fine. In A, an object is created without explicit reference. This is known as anonymous object. # 19. Which of the following statements are correct? a. When creating a Random object, you have to specify the seed or use the default seed. b. If two Random objects have the same seed, the sequence of the random numbers obtained from these two objects are identical. c. The nextInt() method in the Random class returns the next random int value. d. The nextDouble() method in the Random class returns the next random double value. Key:abcd See Figure 9.11. # 20. To obtain the distance between the points (40, 50) and (5.5, 4.4), use a. distance(40, 50, 5.5, 4.4) b. new Point2D(40, 50).distance(5.5, 4.4) c. new Point2D(40, 50).distance(new Point2D(5.5, 4.4)) d. new Point2D(5.5, 4.4).distance(40, 50) e. new Point2D(5.5, 4.4).distance(new Point2D(40, 50)) Key:bcde See Figure 9.12. # Section 9.7 Static Variables, Constants, and Methods 22. You should add the static keyword in the place of ? in Line Line 1 public class Test { Line 2 private int age; Line 3 Line 4 public ? int square(int n) { Line 5 return n * n; Line 6 } ..

in the following code:

Line 7 Line 8 public ? int getAge() { Line 9 return age; Line 10 } Line 11 } a. in line 4 b. in line 8 c. in both line 4 and line 8 d. none Key:a The square method should be static because it does not reference any instance data or invoke any instance method. # 26. What is the output of the second println statement in the main method? public class Foo { int i; static int s; public static void main(String[] args) { Foo f1 = new Foo(); System.out.println("f1.i is " + f1.i + " f1.s is " + f1.s); Foo f2 = new Foo(); System.out.println("f2.i is " + f2.i + " f2.s is " + f2.s); Foo f3 = new Foo(); System.out.println("f3.i is " + f3.i + " f3.s is " + f3.s); } public Foo() { i++; s++; } } a. f2.i is 1 f2.s is 1 b. f2.i is 1 f2.s is 2 c. f2.i is 2 f2.s is 2 d. f2.i is 2 f2.s is 1 Key:b Every Foo object has its own instance variable i, so f2.i is 1. The static variable j is shared by all Foo objects. When f1 is created, j becomes 1. When f2 is created, j becomes 2. # 28. What code may be filled in the blank without causing syntax or runtime errors: public class Test { java.util.Date date; public static void main(String[] args) { Test test = new Test(); System.out.println( } } a. test.date b. date c. test.date.toString() ..

);

d. date.toString() Key:a b and d cause compile errors because date is an instance variable and cannot be accessed from static context. c is wrong because test.date is null, causing NullPointerException. # 23. A method that is associated with an individual object is called a. a static method b. a class method c. an instance method d. an object method Key:c See the third paragraph.

# 24. To declare a constant MAX_LENGTH as a member of the class, you write a. final static MAX_LENGTH = 99.98; b. final static float MAX_LENGTH = 99.98; c. static double MAX_LENGTH = 99.98; d. final double MAX_LENGTH = 99.98; e. final static double MAX_LENGTH = 99.98; Key:e Constants are shared by all objects. # 25.

Analyze the following code.

public class Test { public static void main(String[] args) { int n = 2; xMethod(n); System.out.println("n is " + n); } void xMethod(int n) { n++; } } a. The code has a compile error because xMethod does not return a value. b. The code has a compile error because xMethod is not declared static. c. The code prints n is 1. d. The code prints n is 2. e. The code prints n is 3. Key:b xMethod is declared an instance method. It must be called from an object. So, the program has a compile error in line 4. # 27. What is the output of the third println statement in the main method? public class Foo { int i; static int s; public static void main(String[] args) { Foo f1 = new Foo(); System.out.println("f1.i is " + f1.i + " f1.s is " + f1.s); Foo f2 = new Foo(); ..

System.out.println("f2.i is " + f2.i + " f2.s is " + f2.s); Foo f3 = new Foo(); System.out.println("f3.i is " + f3.i + " f3.s is " + f3.s); } public Foo() { i++; s++; } } a. f3.i is 1 f3.s is 1 b. f3.i is 1 f3.s is 2 c. f3.i is 1 f3.s is 3 d. f3.i is 3 f3.s is 1 e. f3.i is 3 f3.s is 3 Key:c i is an instance variable and s is static, shared by all objects of the Foo class. # 29.

Suppose the xMethod() is invoked in the following constructor in a class, xMethod() is

in the class.

public MyClass() { xMethod(); } a. a static method b. an instance method c. a static method or an instance method Key:c Since xMethod() is not invoked from an object, it must be a static method. # 30. Suppose the xMethod() is invoked from a main method in a class as follows, xMethod() is class. public static void main(String[] args) { xMethod(); } a. a static method b. an instance method c. a static method or an instance method Key:a Since xMethod() is not invoked from an object, it must be a static method. # 21. Variables that are shared by every instance of a class are a. public variables b. private variables c. instance variables d. class variables Key:d See the third paragraph. # Section 9.8 Visibility Modifiers 32. Analyze the following code:

in the

public class Test { public static void main(String args[]) { NClass nc = new NClass(); nc.t = nc.t++; } } class NClass { int t; private NClass() { } } a. The program has a compile error because the NClass class has a private constructor. b. The program does not compile because the parameter list of the main method is wrong. c. The program compiles, but has a runtime error because t has no initial value. d. The program compiles and runs fine. Key:a You cannot use the private constructor to create an object. # 33.

Analyze the following code:

public class Test { private int t; public static void main(String[] args) { int x; System.out.println(t); } } a. The variable t is not initialized and therefore causes errors. b. The variable t is private and therefore cannot be accessed in the main method. c. t is non-static and it cannot be referenced in a static context in the main method. d. The variable x is not initialized and therefore causes errors. e. The program compiles and runs fine. Key:c t is an instance data field. The main method is static. You cannot access t directly from the main method. # 34. Analyze the following code and choose the best answer: public class Foo { private int x; public static void main(String[] args) { Foo foo = new Foo(); System.out.println(foo.x); } } a. Since x is private, it cannot be accessed from an object foo. b. Since x is defined in the class Foo, it can be accessed by any method inside the class without using an object. You can write the code to access x without creating an object such as foo in this code. c. Since x is an instance variable, it cannot be directly used inside a main method. However, it can be accessed through an object such as foo in this code. d. You cannot create a self-referenced object; that is, foo is created inside the class Foo. Key:c (A) is incorrect, since x can be accessed by an object of Foo inside the Foo class. (B) is incorrect because x is ..

non-static, it cannot be accessed in the main method without creating an object. (D) is incorrect, since it is permissible to create an instance of the class within the class. The best choice is (C). # 31. To prevent a class from being instantiated, a. don't use any modifiers on the constructor. b. use the public modifier on the constructor. c. use the private modifier on the constructor. d. use the static modifier on the constructor. Key:c See the last note in this section. # Section 9.9 Data Field Encapsulation 37. Which is the advantage of encapsulation? a. Only public methods are needed. b. Making the class final causes no consequential changes to other code. c. It enables changes to the implementation without changing a class's contract and causes no consequential changes to other code. d. It enables changes to a class's contract without changing the implementation and causes no consequential changes to other code. Key:c See the bullet items at the beginning of this section. # 35. Which of the following statements are true? a. Use the private modifier to encapsulate data fields. b. Encapsulating data fields makes the program easy to maintain. c. Encapsulating data fields makes the program short. d. Encapsulating data fields helps prevent programming errors. Key:abd Read the text in this section. # 36. Suppose you wish to provide an accessor method for a boolean property finished, what should the signature of this method? a. public void getFinished() b. public boolean getFinished() c. public boolean isFinished() d. public void isFinished() Key:c See the signature for a boolean getter method in this section. # 65. Encapsulation means . a. that data fields should be declared private b. that a class can extend another class c. that a variable of supertype can refer to a subtype object d. that a class can contain another class Key:a See the paragraph after the bullet items. # Section 9.10 Passing Objects to Methods 39. What is the value of myCount.count displayed? public class Test { public static void main(String[] args) { Count myCount = new Count(); ..

int times = 0; for (int i = 0; i &lt; 100; i++) increment(myCount, times); System.out.println( "myCount.count = " + myCount.count); System.out.println("times = "+ times); } public static void increment(Count c, int times) { c.count++; times++; } } class Count { int count; Count(int c) { count = c; } Count() { count = 1; } } a. 101 b. 100 c. 99 d. 98 Key:a See Listing 9.10. # 40.

What is the value of times displayed?

public class Test { public static void main(String[] args) { Count myCount = new Count(); int times = 0; for (int i = 0; i &lt; 100; i++) increment(myCount, times); System.out.println( "myCount.count = " + myCount.count); System.out.println("times = "+ times); } public static void increment(Count c, int times) { c.count++; times++; } } ..

class Count { int count; Count(int c) { count = c; } Count() { count = 1; } } a. 101 b. 100 c. 99 d. 98 e. 0 Key:e See Listing 9.10. # 41. What is the output of the following program? import java.util.Date; public class Test { public static void main(String[] args) { Date date = new Date(1234567); m1(date); System.out.print(date.getTime() + " "); m2(date); System.out.println(date.getTime()); } public static void m1(Date date) { date = new Date(7654321); } public static void m2(Date date) { date.setTime(7654321); } } a. 1234567 1234567 b. 1234567 7654321 c. 7654321 1234567 d. 7654321 7654321 Key:b See Listing 9.10. # 38. When invoking a method with an object argument, a. the contents of the object b. a copy of the object c. the reference of the object d. the object is copied, then the reference of the copied object ..

is passed.

Key: c See the Key Point. # Section 9.11 Array of Objects 42. Given the declaration Circle[] x = new Circle[10], which of the following statement is most accurate? a. x contains an array of ten int values. b. x contains an array of ten objects of the Circle type. c. x contains a reference to an array and each element in the array can hold a reference to a Circle object. d. x contains a reference to an array and each element in the array can hold a Circle object. Key:c See the second paragraph of this section. # 43. Assume java.util.Date[] dates = new java.util.Date[10], which of the following statements are true? a. dates is null. b. dates[0] is null. c. dates = new java.util.Date[5] is fine, which assigns a new array to dates. d. dates = new Date() is fine, which creates a new Date object and assigns to dates. Key:bc In A, An array is assigned to dates. So dates is not null. In D, dates is of the type Date[]. You cannot assign a Date object to it. B and C are correct. # Section 9.12 Immutable Objects and Classes 44. Which of the following statements are true about an immutable object? a. The contents of an immutable object cannot be modified. b. All properties of an immutable object must be private. c. All properties of an immutable object must be of primitive types. d. A readable object type property in an immutable object must also be immutable. e. An immutable object contains no mutator methods. Key:abde Read this short section. # Section 9.13 Scope of Variables 45. What is the output for the first print statement in the main method? public class Foo { static int i = 0; static int j = 0; public static void main(String[] args) { int i = 2; int k = 3; { int j = 3; System.out.println("i + j is " + i + j); } k = i + j; System.out.println("k is " + k); System.out.println("j is " + j); } } a. b. c. ..

i + j is 5 i + j is 6 i + j is 22

d. i + j is 23 Key:d The first + operator in the expression "i + j is " + i + j is evaluated. # 46.

What is the output for the second print statement in the main method?

public class Foo { static int i = 0; static int j = 0; public static void main(String[] args) { int i = 2; int k = 3; { int j = 3; System.out.println("i + j is " + i + j); } k = i + j; System.out.println("k is " + k); System.out.println("j is " + j); } } a. k is 0 b. k is 1 c. k is 2 d. k is 3 Key:c When computing k = i + j, i is 2 and j is 0. # 47. What is the output for the third print statement in the main method? public class Foo { static int i = 0; static int j = 0; public static void main(String[] args) { int i = 2; int k = 3; { int j = 3; System.out.println("i + j is " + i + j); } k = i + j; System.out.println("k is " + k); System.out.println("j is " + j); } } a. j is 0 b. j is 1 c. j is 2 d. j is 3 Key:a j is declared and assigned 0 as a static variable. It is redeclared and assigned 3 as a local variable. The scope of ..

the local variable ends at the end of the block before it is printed. So, when it is printed in the third print statement, the static variable j is used. # 48. You can declare two variables with the same name in . a. a method, one as a formal parameter and the other as a local variable b. a block c. two nested blocks in a method (two nested blocks means one being inside the other) d. different methods in a class Key:d Local variables in different methods are complete unrelated. # Section 9.14 The this Keyword 49. Analyze the following code: class Circle { private double radius; public Circle(double radius) { radius = radius; } } a. The program has a compile error because it does not have a main method. b. The program will compile, but you cannot create an object of Circle with a specified radius. The object will always have radius 0. c. The program has a compile error because you cannot assign radius to radius. d. The program does not compile because Circle does not have a default constructor. Key:b You have replaced radius = radius by this.radius = radius # Section 9.14.1 Using this to Reference Data Fileds 51. Which of the following can be placed in the blank line in the following code? public class Test { private int id; public void m1() { .id = 45; } } a. this b. Test c. self d. This Key:a id is an instance data field. # Section 9.14.2 Using this to Invoke a Constructor 50. Analyze the following code: class Test { private double i;

public Test(double i) { this.t(); this.i = i; } public Test() { System.out.println("Default constructor"); this(1); } public void t() { System.out.println("Invoking t"); } } a. this.t() may be replaced by t(). b. this.i may be replaced by i. c. this(1) must be called before System.out.println("Default constructor"). d. this(1) must be replaced by this(1.0). Key:ac In A, See Section 9.14.1. Correct. There are total two correct choices. In B, See Section 9.14.1. In C, See Section 9.14.2. Correct. There are total two correct choices. In D, this(1.0) will be same as this(1) in this case.

Chapter 10 Object-Oriented Thinking Section 10.4 Class Relationships 1. is attached to the class of the composing class to denote the aggregation relationship with the composed object. a. An empty diamond b. A solid diamond c. An empty oval d. A solid oval Key:a See Figure 10.6. # 2. An aggregation relationship is usually represented as a. a data field/the aggregating class b. a data field/the aggregated class c. a method/the aggregating class d. a method/the aggregated class Key:a See Figure 10.7.

# 67. Composition means . a. that data fields should be declared private a. that data fields should be declared private b. that a class extends another class c. that a variable of supertype refers to a subtype object d. that a class contains a data field that references another object Key:d See Section 10.4.2. # Section 10.7 Processing Primitive Data Type Values as Objects 3. Which of the following statements will convert a string s into i of int type? a. i = Integer.parseInt(s); b. i = (new Integer(s)).intValue(); c. i = Integer.valueOf(s).intValue(); d. i = Integer.valueOf(s); e. i = (int)(Double.parseDouble(s)); Key:abcde All fine. d performs an auto conversion from an Integer object to int. # 4. Which of the following statements will convert a string s into a double value d? a. d = Double.parseDouble(s); b. d = (new Double(s)).doubleValue(); c. d = Double.valueOf(s).doubleValue(); d. All of the above. Key:d All are fine. a is preferred because it does not have to create an object. # 6. Which of the following statements are correct? a. Integer.parseInt("12", 2); b. Integer.parseInt(100); c. Integer.parseInt("100"); d. Integer.parseInt(100, 16); e. Integer.parseInt("345", 8); ..

Key:ce A is incorrect because 12 is not a binary number. (B) and (D) are incorrect because the first argument in the parseInt method must be a string. # 7. What is the output of Integer.parseInt("10", 2)? a. 1; b. 2; c. 10; d. Invalid statement; Key:b Based on 2, 10 is 2 in decimal. # 5. Which of the following statements convert a double value d into a string s? a. s = Double.valueOf(d).toString(); b. s = d; c. s = Double.valueOf(d).stringOf(); d. s = String.stringOf(d); e. s = d + ""; Key:ae In a, Double.valueOf(d) creates a Double object for d and the toString() method returns the string representation for the object. In E, d is concatenated with "". # Section 10.8 Automatic Conversion Between Primitive Types and Wrapper Class Types 8. You may directly assign a primitive data type value to a wrapper object. This is called a. auto boxing b. auto unboxing c. auto conversion d. auto casting Key:a See the first paragraph. # 9. Analyze the following code. Line 1: Integer[] intArray = {1, 2, 3}; Line 2: int i = intArray[0] + intArray[1]; Line 3: int j = i + intArray[2]; Line 4: double d = intArray[0]; a. It is OK to assign 1, 2, 3 to an array of Integer objects in JDK 1.5. b. It is OK to automatically convert an Integer object to an int value in Line 2. c. It is OK to mix an int value with an Integer object in an expression in Line 3. d. Line 4 is OK. An int value from intArray[0] object is assigned to a double variable d. Key:abcd See the diagram in this section. # Section 10.9 The BigInteger and BigDecimal Classes 10. To create an instance of BigInteger for 454, use a. BigInteger(454); b. new BigInteger(454); c. BigInteger("454"); d. new BigInteger("454"); Key:ad See the first paragraph. # 13. To add BigInteger b1 to b2, you write ..

a. b1.add(b2); b. b2.add(b1); c. b2 = b1.add(b2); d. b2 = b2.add(b1); e. b1 = b2.add(b1); Key:cd Please note that b2.add(b1) returns a new BigInteger. b2 is not changed. Only (C) and (D) will assign the new big integer to b2. # 14. What is the output of the following code? public class Test { public static void main(String[] args) { java.math.BigInteger x = new java.math.BigInteger("3"); java.math.BigInteger y = new java.math.BigInteger("7"); x.add(y); System.out.println(x); } } a. 3 b. 4 c. 10 d. 11 Key:a Note taht x.add(y) does not change the content of x. # 11. To create an instance of BigDecimal for 454.45, use a. BigDecimal(454.45); b. new BigDecimal(454.45); c. BigDecimal("454.45"); d. new BigDecimal("454.45"); Key:bd # 12. BigInteger and BigDecimal are immutable. a. true b. false Key:a See the first paragraph in this section. # 15. To divide BigDecimal b1 by b2 and assign the result to b1, you write a. b1.divide(b2); b. b2.divide(b1); c. b1 = b1.divide(b2, 20, RoundingMode.HALF_UP); d. b1 = b2.divide(b1, 20, RoundingMode.HALF_UP); e. b2 = b2.divide(b1, 20, RoundingMode.HALF_UP); Key:c See the first paragraph in this section. # 16. Which of the following classes are immutable? a. Integer b. Double c. BigInteger d. BigDecimal ..

e. String Key:abcde All the number classes and the String class are immutable. # 17. Which of the following statements are correct? a. new java.math.BigInteger("343"); b. new java.math.BigDecimal("343.445"); c. new java.math.BigInteger(343); d. new java.math.BigDecimal(343.445); Key:abd The constructor for BigDecimal has to be new BigDecimal("number_string"). # Section 10.10 The String Class 18. Which of the following statements is preferred to create a string "Welcome to Java"? a. String s = "Welcome to Java"; b. String s = new String("Welcome to Java"); c. String s; s = "Welcome to Java"; d. String s; s = new String("Welcome to Java"); Key:a (a) is better than (b) because the string created in (a) is interned. Since strings are immutable and are ubiquitous in programming, to improve efficiency and save memory, the JVM uses a unique instance for string literals with the same character sequence. Such an instance is called interned. The JVM (a) is simpler than (c). # 27.

Analyze the following code.

class Test { public static void main(String[] args) { String s; System.out.println("s is " + s); } } a. The program has a compile error because s is not initialized, but it is referenced in the println statement. b. The program has a runtime error because s is not initialized, but it is referenced in the println statement. c. The program has a runtime error because s is null in the println statement. d. The program compiles and runs fine. Key:a s is a local variable. Before its use, a value must be assigned to it. # Section 10.10.1 Immutable Strings and Interned Strings 19. What is the output of the following code? public class Test { public static void main(String[] args) { String s1 = "Welcome to Java!"; String s2 = s1; if (s1 == s2) System.out.println( "s1 and s2 reference to the same String object"); else System.out.println( "s1 and s2 reference to different String objects"); } } ..

a. s1 and s2 reference to the same String object b. s1 and s2 reference to different String objects Key:a s2 = s1 assigns s1 to s2. Now s1 and s2 have the same references. # 20.

What is the output of the following code?

public class Test { public static void main(String[] args) { String s1 = "Welcome to Java!"; String s2 = "Welcome to Java!"; if (s1 == s2) System.out.println( "s1 and s2 reference to the same String object"); else System.out.println( "s1 and s2 reference to different String objects"); } } a. s1 and s2 reference to the same String object b. s1 and s2 reference to different String objects Key:a Since strings are immutable and are ubiquitous in programming, to improve efficiency and save memory, the JVM uses a unique instance for string literals with the same character sequence. Such an instance is called interned. # 21.

What is the output of the following code?

public class Test { public static void main(String[] args) { String s1 = new String("Welcome to Java!"); String s2 = new String("Welcome to Java!"); if (s1 == s2) System.out.println( "s1 and s2 reference to the same String object"); else System.out.println( "s1 and s2 reference to different String objects"); } } a. s1 and s2 reference to the same String object b. s1 and s2 reference to different String objects Key:b s1 and s2 are two difference objects. They have the same content, but are created using the new operator. # 22.

What is the output of the following code?

public class Test { public static void main(String[] args) { String s1 = new String("Welcome to Java!"); String s2 = new String("Welcome to Java!"); if (s1.equals(s2)) ..

System.out.println("s1 and s2 have the same contents"); else System.out.println("s1 and s2 have different contents"); } } a. s1 and s2 have the same contents b. s1 and s2 have different contents Key:a s1 and s2 are two difference objects, but they have the same content. # 23.

What is the output of the following code?

public class Test { public static void main(String[] args) { String s1 = new String("Welcome to Java!"); String s2 = s1.toUpperCase(); if (s1 == s2) System.out.println("s1 and s2 reference to the same String object"); else if (s1.equals(s2)) System.out.println("s1 and s2 have the same contents"); else System.out.println("s1 and s2 are of different objects"); } } a. s1 and s2 reference to the same String object b. s1 and s2 have the same contents c. s1 and s2 are of different objects Key:c s1.toUpperCase() returns a new object. # 24.

What is the output of the following code?

public class Test { public static void main(String[] args) { String s1 = new String("Welcome to Java"); String s2 = s1; s1 += "and Welcome to HTML"; if (s1 == s2) System.out.println( "s1 and s2 reference to the same String object"); else System.out.println( "s1 and s2 reference to different String objects"); } } a. s1 and s2 reference to the same String object b. s1 and s2 reference to different String objects Key:b s1 += "and Welcome to HTML"; obtains a new object in s1. So, s1 and s2 are two objects. # 25. Suppose s1 and s2 are two strings. Which of the following statements or expressions are incorrect? ..

a. String s = new String("new string"); b. String s3 = s1 + s2 c. s1 &gt;= s2 d. int i = s1.length e. s1.charAt(0) = '5' Key:cde Strings cannot be compared using relational operators (&lt;, &le;, &gt;, &ge;). The length() is a method for strings. Cannot set a character in a string. So, C, D, and E are incorrect. # Section 10.10.2 Replacing and Splitting Strings 26. What is the output of the following code? String s = "University"; s.replace("i", "ABC"); System.out.println(s); a. UnABCversity b. UnABCversABCty c. UniversABCty d. University Key:d No method in the String class can change the content of the string. String is an immutable class. # 30. Assume s is "ABCABC", the method returns a new string "aBCaBC". a. s.toLowerCase(s) b. s.toLowerCase() c. s.replace('A', 'a') d. s.replace('a', 'A') e. s.replace("ABCABC", "aBCaBC") Key:ce In (C), 'A' is replaced by a. In (E), "ABCABC" is replaced by "aBCaBC". # 35. What is displayed by the following code? public static void main(String[] args) { String[] tokens = "Welcome to Java".split("o"); for (int i = 0; i < tokens.length; i++) { System.out.print(tokens[i] + " "); } } a. Welcome to Java b. Welc me to Java c. Welc me t Java d. Welcome t Java Key:c "Welcome to Java".split("o") splits the string into {"Welc", "me t", " Java"}. # 34. What is displayed by the following statement? System.out.println("Java is neat".replaceAll("is", "AAA")); a. JavaAAAneat b. JavaAAA neat c. Java AAA neat d. Java AAAneat ..

Key:c "is" replaced by "AAA" in "Java is neat". So "Java is neat".replaceAll("is", "AAA") returns "Java AAA neat". # Section 10.10.3 Matching, Replacing, and Splitting by Patterns 36. What is displayed by the following code? System.out.print("Hi, ABC, good".matches("ABC ") + " "); System.out.println("Hi, ABC, good".matches(".*ABC.*")); a. false false b. true false c. true true d. false true Key:d "Hi, ABC, good" does not match "ABC ". "Hi, ABC, good" matches the regex ".*ABC.*". The regex .* means zero or more any characters. # 37. What is displayed by the following code? System.out.print("A,B;C".replaceAll(",;", "#") + " "); System.out.println("A,B;C".replaceAll("[,;]", "#")); a. A B C A#B#C b. A#B#C A#B#C c. A,B;C A#B#C d. ABCABC Key:c The regex [,;] means character , or ;. "A,B;C".replaceAll("[,;]", "#") returns "A#B#C". # 38. What is displayed by the following code? String[] tokens = "A,B;C;D".split("[,;]"); for (int i = 0; i < tokens.length; i++) System.out.print(tokens[i] + " "); a. A,B;C;D b. ABCD c. A B C;D d. A B;C;D Key:b "A,B;C;D".split("[,;]") splits it into {"A", "B", "C", "D"}. # Section 10.10.4 Conversion between Strings and Arrays 28. Which of the following is the correct statement to return a string from an array a of characters? a. toString(a) b. new String(a) c. convertToString(a) d. String.toString(a) Key:b See the String constructor in Section 10.10. # 29. Assume s is " abc ", the method a. s.trim(s) b. trim(s) c. String.trim(s) d. s.trim() ..

returns a new string "abc".

Key:d The trim() method trims the whitespace characters from both the left and right sides of the string. # 31. Assume s is "ABCABC", the method returns an array of characters. a. toChars(s) b. s.toCharArray() c. String.toChars() d. String.toCharArray() e. s.toChars() Key:b The toCharArray() returns an array of characters from the string. # Section 10.10.5 Converting Characters and Numeric Values 32. returns a string. a. String.valueOf(123) b. String.valueOf(12.53) c. String.valueOf(false) d. String.valueOf(new char[]{'a', 'b', 'c'}) Key:abcd See Figure 10.17. # Section 10.11 The StringBuilder/StringBuffer Class 33. The following program displays . public class Test { public static void main(String[] args) { String s = "Java"; StringBuilder builder = new StringBuilder(s); change(s); System.out.println(s); } private static void change(String s) { s = s + " and HTML"; } } a. Java b. Java and HTML c. and HTML d. nothing is displayed Key:a Inside the method, the statement s = s + " and HTML" creates a new String object s, which is different from the original String object passed to the change(s) method. The original String object has not been changed. Therefore, the output from the original string is Java. # Section 10.11.1 Modifying Strings in the StringBuilder 39. Analyze the following code. class Test { public static void main(String[] args) { StringBuilder strBuilder = new StringBuilder(4); strBuilder.append("ABCDE"); System.out.println("What's strBuilder.charAt(5)? " ..

+ strBuilder.charAt(5)); } } a. The program has a compile error because you cannot specify initial capacity in the StringBuilder constructor. b. The program has a runtime error because because the builder's capacity is 4, but five characters "ABCDE" are appended into the builder. c. The program has a runtime error because the length of the string in the builder is 5 after "ABCDE" is appended into the builder. Therefore, strBuilder.charAt(5) is out of range. d. The program compiles and runs fine. Key:c The charAt method returns the character at a specific index in the string builder. The first character of a string builder is at index 0, the next at index 1, and so on. The index argument must be greater than or equal to 0, and less than the length of the string builder. # 46. The following program displays

public class Test { public static void main(String[] args) { String s = "Java"; StringBuilder builder = new StringBuilder(s); change(builder); System.out.println(builder); } private static void change(StringBuilder builder) { builder.append(" and HTML"); } } a. Java b. Java and HTML c. and HTML d. nothing is displayed Key:b Inside the method, the content of the StringBuilder object is changed to Java and HTML. Therefore, the output from builder is Java and HTML. # 40. Which of the following is true? a. You can add characters into a string builder. b. You can delete characters from a string builder. c. You can reverse the characters in a string buffer. d. The capacity of a string buffer can be automatically adjusted. Key:abcd Read toward the end of this section. # 42. Assume StringBuilder strBuilder is "ABCDEFG", after invoking a. strBuilder.delete(0, 3) b. strBuilder.delete(1, 3) c. strBuilder.delete(1, 4) d. strBuilder.delete(2, 4) Key:c See the discussion of the delete method in this section. # 43. Assume StringBuilder strBuilder is "ABCDEFG", after invoking ..

, strBuilder contains "AEFG".

, strBuilder contains

"ABCRRRRDEFG". a. strBuilder.insert(1, "RRRR") b. strBuilder.insert(2, "RRRR") c. strBuilder.insert(3, "RRRR") d. strBuilder.insert(4, "RRRR") Key:c See the discussion of the insert method in this section. # 44. Assume StringBuilder strBuilder is "ABCCEFC", after invoking a. strBuilder.replace('C', 'T') b. strBuilder.replace("C", "T") c. strBuilder.replace("CC", "TT") d. strBuilder.replace('C', "TT") e. strBuilder.replace(2, 7, "TTEFT") Key:e See the discussion of the replace method in this section.

, strBuilder contains "ABTTEFT".

# 45. The StringBuilder methods not only change the contents of a string builder, but also returns a reference to the string builder. a. delete b. append c. insert d. reverse e. replace Key:abcde All the modification methods in the StringBuilder class modify the StringBuilder content and also returns the reference of the StringBuilder. # Section 10.11.2 The toString, capacity, length, setLength, and charAt Methods 41. returns the last character in a StringBuilder variable named strBuilder? a. strBuilder.charAt(strBuilder.length() - 1) b. strBuilder.charAt(strBuilder.capacity() - 1) c. StringBuilder.charAt(strBuilder.length() - 1) d. StringBuilder.charAt(strBuilder.capacity() - 1) Key:a See Figure 10.20.

Chapter 11 Inheritance and Polymorphism Section 11.2 Superclasses and Subclasses 1. Object-oriented programming allows you to derive new classes from existing classes. This is called a. encapsulation b. inheritance c. abstraction d. generalization Key:b See the first paragraph.

# 2. Which of the following statements are true? a. A subclass is a subset of a superclass. b. A subclass is usually extended to contain more functions and more detailed information than its superclass. c. "class A extends B" means A is a subclass of B. d. "class A extends B" means B is a subclass of A. Key:bc Read toward the end of this section. # 66. Inheritance means . a. that data fields should be declared private b. that a class can extend another class c. that a variable of supertype can refer to a subtype object d. that a class can contain another class Key:b See the Key Point. # Section 11.3 Using the super Keyword Section 11.3.1 Calling Superclass Constructors 3. Suppose you create a class Square to be a subclass of GeometricObject. Analyze the following code: class Square extends GeometricObject { double length; Square(double length) { GeometricObject(length); } } a. The program compiles fine, but you cannot create an instance of Square because the constructor does not specify the length of the Square. b. The program has a compile error because you attempted to invoke the GeometricObject class's constructor illegally. c. The program compiles fine, but it has a runtime error because of invoking the Square class's constructor illegally. Key:b You have to use super() or super(withapproriatearguments) to invoke a super class constructor explicitly. # 4. Analyze the following code: public class A extends B { } class B { public B(String s) { } © 2020 Pearson Education, Inc., Hoboken, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist.

} a. The program has a compile error because A does not have a default constructor. b. The program has a compile error because the default constructor of A invokes the default constructor of B, but B does not have a default constructor. c. The program would compile fine if you add the following constructor into A: A(String s) { } d. The program would compile fine if you add the following constructor into A: A(String s) { super(s); } Key:bd The class A has a default constructor, which invokes the superclass B's no-arg constructor. But B has no noarg constructor. This causes an error. # 5.

Analyze the following code:

public class Test extends A { public static void main(String[] args) { Test t = new Test(); t.print(); } } class A { String s; A(String s) { this.s = s; } public void print() { System.out.println(s); } } a. The program does not compile because Test does not have a default constructor Test(). b. The program has an implicit default constructor Test(), but it cannot be compiled, because its super class does not have a default constructor. The program would compile if the constructor in the class A were removed. c. The program would compile if a default constructor A(){ } is added to class A explicitly. d. The program compiles, but it has a runtime error due to the conflict on the method name print. Key:bc The class Test has a default constructor, which invokes the superclass A's no-arg constructor. But A has no noarg constructor. This causes an error. # Section 11.3.2 Constructor Chaining 6. What is the output of running class C? class A { public A() { System.out.println( "The default constructor of A is invoked"); } } class B extends A { public B() { System.out.println( "The default constructor of B is invoked"); } © 2020 Pearson Education, Inc., Hoboken, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist.

} public class C { public static void main(String[] args) { B b = new B(); } } a. Nothing displayed b. "The default constructor of B is invoked" c. "The default constructor of A is invoked" followed by "The default constructor of B is invoked" d. "The default constructor of B is invoked" followed by "The default constructor of A is invoked" e. "The default constructor of A is invoked" Key:c Superclass's constructor is called before executing the statements in the subclass constructor. # 7. Which of the following is incorrect? a. A constructor may be static. b. A constructor may be private. c. A constructor may invoke a static method. d. A constructor may invoke an overloaded constructor. e. A constructor invokes its superclass no-arg constructor by default if a constructor does not invoke an overloaded constructor or its superclass’s constructor. Key:a A constructor cannot be static, because you use a constructor to create a specific instance. A constructor may be private. In this case, the use cannot create an instance using this constructor. For example, the constructor in the Math class is private. A constructor may invoke a static method just like any method can invoke a static method. A constructor can invoke an overloaded constructor using the this keyword. So, the correct answer is A. # Section 11.3.3 Calling Superclass Methods 8. Which of the statements regarding the super keyword is incorrect? a. You can use super to invoke a super class constructor. b. You can use super to invoke a super class method. c. You can use super.super.p to invoke a method in superclass's parent class. d. You cannot invoke a method in superclass's parent class. Key:c Using super.super is not allowed in Java. So, the answer to this question is C. # Section 11.4 Overriding Methods 9. Analyze the following code: public class Test { public static void main(String[] args) { B b = new B(); b.m(5); System.out.println("i is " + b.i); } } class A { int i; public void m(int i) { this.i = i; } © 2020 Pearson Education, Inc., Hoboken, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist.

} class B extends A { public void m(String s) { } } a. The program has a compile error, because m is overridden with a different signature in B. b. The program has a compile error, because b.m(5) cannot be invoked since the method m(int) is hidden in B. c. The program has a runtime error on b.i, because i is not accessible from b. d. The method m is not overridden in B. B inherits the method m from A and defines an overloaded method m in B. Key:d See the Key Point in this section. # 10. The getValue() method is overridden in two ways. Which one is correct? I: public class Test { public static void main(String[] args) { A a = new A(); System.out.println(a.getValue()); } } class B { public String getValue() { return "Any object"; } } class A extends B { public Object getValue() { return "A string"; } } II: public class Test { public static void main(String[] args) { A a = new A(); System.out.println(a.getValue()); } } class B { public Object getValue() { return "Any object"; } } class A extends B { public String getValue() { return "A string"; } } file:///C|/Users/usuller/Downloads/chapter11.txt[12/4/2019 3:47:54 PM]

a. I b. II c. Both I and II d. Neither Key:b See the text at the end of the section. # Section 11.5 Overriding vs. Overloading 11. Which of the following statements are true? a. To override a method, the method must be defined in the subclass using the same signature and compatible return type as in its superclass. b. Overloading a method is to provide more than one method with the same name but with different signatures to distinguish them. c. It is a compile error if two methods differ only in return type in the same class. d. A private method cannot be overridden. If a method defined in a subclass is private in its superclass, the two methods are completely unrelated. e. A static method cannot be overridden. If a static method defined in the superclass is redefined in a subclass, the method defined in the superclass is hidden. Key:abcde See the text at the end of the section. # 13. Analyze the following code: public class Test { public static void main(String[] args) { new B(); } } class A { int i = 7; public A() { System.out.println("i from A is " + i); } public void setI(int i) { this.i = 2 * i; } } class B extends A { public B() { setI(20); // System.out.println("i from B is " + i); } @Override public void setI(int i) { this.i = 3 * i; } } a. The constructor of class A is not called. file:///C|/Users/usuller/Downloads/chapter11.txt[12/4/2019 3:47:54 PM]

b. The constructor of class A is called and it displays "i from A is 7". c. The constructor of class A is called and it displays "i from A is 40". d. The constructor of class A is called and it displays "i from A is 60". Key:b When invoking new B(), B's superclass A's constructor is invoked first. So it displays i from A is 7. # 14. Analyze the following code: public class Test { public static void main(String[] args) { new B(); } } class A { int i = 7; public A() { setI(20); System.out.println("i from A is " + i); } public void setI(int i) { this.i = 2 * i; } } class B extends A { public B() { // System.out.println("i from B is " + i); } @Override public void setI(int i) { this.i = 3 * i; } } a. The constructor of class A is not called. b. The constructor of class A is called and it displays "i from A is 7". c. The constructor of class A is called and it displays "i from A is 40". d. The constructor of class A is called and it displays "i from A is 60". Key:d When invoking new B(), B's superclass A's constructor is invoked first. It invokes setI(20). The setI method in B is used because object created is new B(). The setI method in B assigns 3 * 20 to i. So it displays i from A is 60. # 12. Which of the following statements are true? a. A method can be overloaded in the same class. b. A method can be overridden in the same class. c. If a method overloads another method, these two methods must have the same signature. d. If a method overrides another method, these two methods must have the same signature. e. A method in a subclass can overload a method in the superclass. Key:ade See the text at the end of the section. # file:///C|/Users/usuller/Downloads/chapter11.txt[12/4/2019 3:47:54 PM]

Section 11.6 The Object Class and Its toString() Method 15. Analyze the following code: public class Test { public static void main(String[] args) { Object a1 = new A(); Object a2 = new Object(); System.out.println(a1); System.out.println(a2); } } class A { int x; @Override public String toString() { return "A's x is " + x; } } a. The program cannot be compiled, because System.out.println(a1) is wrong and it should be replaced by System.out.println(a1.toString()); b. When executing System.out.println(a1), the toString() method in the Object class is invoked. c. When executing System.out.println(a2), the toString() method in the Object class is invoked. d. When executing System.out.println(a1), the toString() method in the A class is invoked. Key:cd Since a1 is an instance of A, the toString() method in the A class is invoked at runtime. # Section 11.7 Polymorphism 17. Given the following code, find the compile error. public class Test { public static void main(String[] args) { m(new GraduateStudent()); m(new Student()); m(new Person()); m(new Object()); } public static void m(Student x) { System.out.println(x.toString()); } } class GraduateStudent extends Student { } class Student extends Person { @Override public String toString() { return "Student"; } }

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class Person extends Object { @Override public String toString() { return "Person"; } } a. m(new GraduateStudent()) causes an error b. m(new Student()) causes an error c. m(new Person()) causes an error d. m(new Object()) causes an error Key:cd You cannot pass a supertype variable to a subtype without explicit casting. # 64. Polymorphism means . a. that data fields should be declared private b. that a class can extend another class c. that a variable of supertype can refer to a subtype object d. that a class can contain another class Key:c See the Key Point. # Section 11.8 Dynamic Binding 18. What is the output of the following code? public class Test { public static void main(String[] args) { new Person().printPerson(); new Student().printPerson(); } } class Student extends Person { @Override public String getInfo() { return "Student"; } } class Person { public String getInfo() { return "Person"; } public void printPerson() { System.out.println(getInfo()); } } a. Person Person b. Person Student c. Student Student d. Student Person Key:b See LiveExample 11.6.

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# 19. What is the output of the following code? public class Test { public static void main(String[] args) { new Person().printPerson(); new Student().printPerson(); } } class Student extends Person { private String getInfo() { return "Student"; } } class Person { private String getInfo() { return "Person"; } public void printPerson() { System.out.println(getInfo()); } } a. Person Person b. Person Student c. Student Student d. Student Person Key:a Note that the getInfo method is private in Person. It is not known to the outside of the class. This is the method invoked from the printPerson() method. # 16. Which of the following statements is false? a. You can always pass an instance of a subclass to a parameter of its superclass type. This feature is known as polymorphism. b. The compiler finds a matching method according to parameter type, number of parameters, and order of the parameters at compile time. c. A method may be implemented in several subclasses. The Java Virtual Machine dynamically binds the implementation of the method at runtime. d. Dynamic binding can apply to static methods. e. Dynamic binding can apply to instance methods. Key:d Dynamic binding is applied to instance methods, not static methods. Static methods are bound in the compile time. # Section 11.9 Casting Objects and the instanceof Operator 20. Which of the following are Java keywords? a. instanceOf b. instanceof c. cast d. casting Key:b A simple rule: the keywords are all in lowercase. file:///C|/Users/usuller/Downloads/chapter11.txt[12/4/2019 3:47:54 PM]

# 25. Analyze the following code: public class Test { public static void main(String[] args) { String s = new String("Welcome to Java"); Object o = s; String d = (String)o; } } a. When assigning s to o in Object o = s, a new object is created. b. When casting o to s in String d = (String)o, a new object is created. c. When casting o to s in String d = (String)o, the contents of o is changed. d. s, o, and d reference the same String object. Key:d Casting object reference variable does not affect the contents of the object. # 22.

Assume Cylinder is a subtype of Circle. Analyze the following code:

Circle c = new Circle (5); Cylinder c = cy; a. The code has a compile error. b. The code has a runtime error. c. The code is fine. Key:a You cannot assign a variable of a supertype to a subtype without explicit casting. # 23.

Given the following classes and their objects:

class C1 {}; class C2 extends C1 {}; class C3 extends C1 {}; C2 c2 = new C2(); C3 c3 = new C3(); Analyze the following statement: c2 = (C2)((C1)c3); a. c3 is cast into c2 successfully. b. You will get a runtime error because you cannot cast objects from sibling classes. c. You will get a runtime error because the Java runtime system cannot perform multiple casting in nested form. d. The statement is correct. Key:b c3 can be casted to C1, but not to C2. # 24.

Given the following code, which of the following expressions evaluates to false?

class C1 {} class C2 extends C1 { } class C3 extends C2 { } class C4 extends C1 {}

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C1 c1 = new C1(); C2 c2 = new C2(); C3 c3 = new C3(); C4 c4 = new C4(); a. c1 instanceof C1 b. c2 instanceof C1 c. c3 instanceof C1 d. c4 instanceof C2 Key:d c4 is not an instace of C2. # 26. You can assign to a variable of Object[] type. a. new char[100] b. new int[100] c. new double[100] d. new String[100] e. new java.util.Date[100] Key:de Primitive data type array is not compatible with Object[]. # 21.

Assume Cylinder is a subtype of Circle. Analyze the following code:

Cylinder cy = new Cylinder(1, 1); Circle c = cy; a. The code has a compile error. b. The code has a runtime error. c. The code is fine. Key:c You can assign a variable of a subtype to a supertype. # Section 11.10 The Object’s equals() Method 33. Analyze the following code. // Program 1: public class Test { public static void main(String[] args) { Object a1 = new A(); Object a2 = new A(); System.out.println(a1.equals(a2)); } } class A { int x; public boolean equals(Object a) { return this.x == ((A)a).x; } } // Program 2: public class Test { file:///C|/Users/usuller/Downloads/chapter11.txt[12/4/2019 3:47:54 PM]

public static void main(String[] args) { Object a1 = new A(); Object a2 = new A(); System.out.println(a1.equals(a2)); } } class A { int x; public boolean equals(A a) { return this.x == a.x; } } a. Program 1 displays true and Program 2 displays true b. Program 1 displays false and Program 2 displays true c. Program 1 displays true and Program 2 displays false d. Program 1 displays false and Program 2 displays false Key:c In Program 1, the equals method in the Object class is overridden. a1.equals(a2) invokes this method. It returns true. In Program 2, the equals method in the Object class is not overridden. a1.equals(a2) invokes the equals method defined in the Object class, which returns false in this case. # 34. Analyze the following code. // Program 1: public class Test { public static void main(String[] args) { Object a1 = new A(); Object a2 = new A(); System.out.println(a1.equals(a2)); } } class A { int x; public boolean equals(A a) { return this.x == a.x; } } // Program 2: public class Test { public static void main(String[] args) { A a1 = new A(); A a2 = new A(); System.out.println(a1.equals(a2)); } } class A { int x; file:///C|/Users/usuller/Downloads/chapter11.txt[12/4/2019 3:47:54 PM]

public boolean equals(A a) { return this.x == a.x; } } a. Program 1 displays true and Program 2 displays true b. Program 1 displays false and Program 2 displays true c. Program 1 displays true and Program 2 displays false d. Program 1 displays false and Program 2 displays false Key:b In Program 1, the equals method in the Object class is invoked. In Program 2, the equals method in the class A is invoked. There are now two overloaded methods available in the class A. i.e. public boolean equals(Object a) and public boolean equals(A a). Which of the two is used by a1.equals(a2) is determined at compile time. a1.equals(a2) in Program 1 matches the equals method defined in Object and a1.equals(a2) in Program 2 matches the equals method defined in the class A. # 35. Analyze the following code. // Program 1 public class Test { public static void main(String[] args) { Object a1 = new A(); Object a2 = new A(); System.out.println(((A)a1).equals((A)a2)); } } class A { int x; public boolean equals(A a) { return this.x == a.x; } } // Program 2 public class Test { public static void main(String[] args) { A a1 = new A(); A a2 = new A(); System.out.println(a1.equals(a2)); } } class A { int x; public boolean equals(A a) { return this.x == a.x; } } a. Program 1 displays true and Program 2 displays true b. Program 1 displays false and Program 2 displays true file:///C|/Users/usuller/Downloads/chapter11.txt[12/4/2019 3:47:54 PM]

c. Program 1 displays true and Program 2 displays false d. Program 1 displays false and Program 2 displays false Key:a In Program 1, ((A)a1).equals((A)a2) matches the equals(A a) method in the class A. # 27. The equals method is defined in the Object class. Which of the following is correct to override it in the String class? a. public boolean equals(String other) b. public boolean equals(Object other) c. public static boolean equals(String other) d. public static boolean equals(Object other) Key:b B is the correct signature for the equals method. # 28. Which of the following statements are true? a. Override the equals(Object) method in the Object class whenever possible. b. Override the toString() method in the Object class whenever possible. c. A public default no-arg constructor is assumed if no constructors are defined explicitly. d. You should follow standard Java programming style and naming conventions. Choose informative names for classes, data fields, and methods. Key:abcd These statements are all correct. # 29. What is the output of the following code? public class Test { public static void main(String[] args) { Object o1 = new Object(); Object o2 = new Object(); System.out.print((o1 == o2) + " " + (o1.equals(o2))); } } a. false false b. true true c. false true d. true false Key:a o1 == o2 is false, since o1 and o2 are two different objects. o1.equals(o2) is false since the equals method returns o1 == o2 in the Object class. # 30. What is the output of the following code? public class Test { public static void main(String[] args) { String s1 = new String("Java"); String s2 = new String("Java"); System.out.print((s1 == s2) + " " + (s1.equals(s2))); } } a. false false b. true true c. false true d. true false Key:c s1 == s2 is false, since s1 and s2 are two different objects. s1.equals(s2) is true since the equals method returns file:///C|/Users/usuller/Downloads/chapter11.txt[12/4/2019 3:47:54 PM]

true if two strings have the same content. # 31. Given two reference variables t1 and t2, if t1 == t2 is true, t1.equals(t2) must be a. true b. false Key:a t1 and t2 refer to the same object. # 32. Given two reference variables t1 and t2, if t1.equals(t2) is true, t1 == t2 a. is always true b. is always false c. may be true or false Key:c Two different objects may be equal with the same contents.

# Section 11.11 The ArrayList Class 43. Analyze the following code: ArrayList<String> list = new ArrayList<>(); list.add("Beijing"); list.add("Tokyo"); list.add("Shanghai"); list.set(3, "Hong Kong"); a. The last line in the code causes a runtime error because there is no element at index 3 in the array list. b. The last line in the code has a compile error because there is no element at index 3 in the array list. c. If you replace the last line by list.add(3, "Hong Kong"), the code will compile and run fine. d. If you replace the last line by list.add(4, "Hong Kong"), the code will compile and run fine. Key:ac There is no element at index 3. # 44. What is the output of the following code? ArrayList<java.util.Date> list = new ArrayList<>(); java.util.Date d = new java.util.Date(); list.add(d); list.add(d); System.out.println((list.get(0) == list.get(1)) + " " + (list.get(0)).equals(list.get(1))); a. true false b. false true c. true true d. false false Key:c list.get(0) and list.get(1) point to the same object. # 45. What is the output of the following code? ArrayList<String> list = new ArrayList<>(); String s1 = new String("Java"); String s2 = new String("Java"); list.add(s1); file:///C|/Users/usuller/Downloads/chapter11.txt[12/4/2019 3:47:54 PM]

list.add(s2); System.out.println((list.get(0) == list.get(1)) + " " + (list.get(0)).equals(list.get(1))); a. true false b. false true c. true true d. false false Key:b list.get(0) and list.get(1) point to two different objects with the same string contents. # 36. You can create an ArrayList using . a. new ArrayList[] b. new ArrayList[100] c. new ArrayList<>() d. ArrayList() Key:c You can create an ArrayListing using its no-arg constructor. Since ArrayList is a generic type, new ArrayList<>() automatically discovers the type in the defining type. For example, ArrayList<String> list = new ArrayList<>(); # 37. Invoking removes all elements in an ArrayList x. a. x.remove() b. x.clean() c. x.delete() d. x.empty() e. x.clear() Key:e See Figure 11.3. # 38. Suppose ArrayList x contains two strings [Beijing, Singapore]. Which of the following methods will cause the list to become [Beijing, Chicago, Singapore]? a. x.add("Chicago") b. x.add(0, "Chicago") c. x.add(1, "Chicago") d. x.add(2, "Chicago") Key:c See Figure 11.3. # 39. Suppose ArrayList x contains two strings [Beijing, Singapore]. Which of the following method will cause the list to become [Beijing]? a. x.remove("Singapore") b. x.remove(0) c. x.remove(1) d. x.remove(2) Key:ac See Figure 11.3. # 40. Suppose ArrayList x contains two strings [Beijing, Singapore]. Which of the following method will cause runtime errors? a. x.get(1) b. x.set(2, "New York"); c. x.get(2) d. x.remove(2) file:///C|/Users/usuller/Downloads/chapter11.txt[12/4/2019 3:47:54 PM]

e. x.size() Key:bcd There is no element at index 2. # 41. Invoking returns the first element in an ArrayList x. a. x.first() b. x.get(0) c. x.get(1) d. x.get() Key:b See Figure 11.3. # 42. Invoking returns the number of the elements in an ArrayList x. a. x.getSize() b. x.getLength(0) c. x.length(1) d. x.size() Key:d See Figure 11.3. # 46. Suppose an ArrayList list contains {"red", "green", "red", "green"}. What is the list after the following code? list.remove("red"); a. {"red", "green", "red", "green"} b. {"green", "red", "green"} c. {"green", "green"} d. {"red", "green", "green"} Key:b See Figure 11.3. # 47. Suppose an ArrayList list contains {"red", "red", "green"}. What is the list after the following code? String element = "red"; for (int i = 0; i < list.size(); i++) if (list.get(i).equals(element)) list.remove(element); a. {"red", "red", "green"} b. {"red", "green"} c. {"green"} d. {} Key:b See Figure 11.3. # 48. Suppose an ArrayList list contains {"red", "red", "green"}. What is the list after the following code? String element = "red"; for (int i = 0; i < list.size(); i++) if (list.get(i).equals(element)) { list.remove(element); i--; }

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a. {"red", "red", "green"} b. {"red", "green"} c. {"green"} d. {} Key:c See Figure 11.3. # 49. Suppose an ArrayList list contains {"red", "red", "green"}. What is the list after the following code? String element = "red"; for (int i = list.size() - 1; i >= 0; i--) if (list.get(i).equals(element)) list.remove(element); a. {"red", "red", "green"} b. {"red", "green"} c. {"green"} d. {} Key:c See Figure 11.3. # 50. The output from the following code is

java.util.ArrayList<String> list = new java.util.ArrayList<>(); list.add("New York"); java.util.ArrayList<String> list1 = list; list.add("Atlanta"); list1.add("Dallas"); System.out.println(list1); a. [New York] b. [New York, Atlanta] c. [New York, Atlanta, Dallas] d. [New York, Dallas] Key:c Listing 11.8. # Section 11.12 Useful Methods for Lists 51. Show the output of the following code: String[] array = {"red", "green", "blue"}; ArrayList<String> list = new ArrayList<>(Arrays.asList(array)); list.add(0, "red"); System.out.println(list); a. ["red", "green", "blue", "red"] b. ["red", "green", "blue"] c. ["red", "red", "green", "blue"] d. ["red", "green", "red", "blue"] Key:c See the discussion of the asList method in this section. # 52.

Analyze the following code:

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Double[] array = {1, 2, 3}; ArrayList<Double> list = new ArrayList<>(Arrays.asList(array)); System.out.println(list); a. The code is correct and displays [1, 2, 3]. b. The code is correct and displays [1.0, 2.0, 3.0]. c. The code has a compile error because an integer such as 1 is automatically converted into an Integer object, but the array element type is Double. d. The code has a compile error because asList(array) requires that the array elements are objects. Key:c See the discussion of the asList method in this section. # 53.

Analyze the following code:

double[] array = {1, 2, 3}; ArrayList<Double> list = new ArrayList<>(Arrays.asList(array)); System.out.println(list); a. The code is correct and displays [1, 2, 3]. b. The code is correct and displays [1.0, 2.0, 3.0]. c. The code has a compile error because an integer such as 1 is automatically converted into an Integer object, but the array element type is Double. d. The code has a compile error because asList(array) requires that the array elements are objects. Key:d See the discussion of the asList method in this section. # 54.

Analyze the following code:

double[] c = {1, 2, 3}; System.out.println(java.util.Collections.max(c)); a. The code is correct and displays 3. b. The code is correct and displays 3.0. c. The code has a compile error on Collections.max(c). c cannot be an array. d. The code has a compile error on double[] c = {1, 2, 3}. Key:c See the discussion of the max method in this section. # 55.

Analyze the following code:

Integer[] c = {3, 5}; java.util.Collections.shuffle(c); System.out.println(java.util.Arrays.toString(c)); a. The code is correct and displays [3, 5]. b. The code is correct and displays [5, 3]. c. The code has a compile error on Collections.shuffle(c). c cannot be an array. d. The code has a compile error on Integer[] c = {3, 5}. Key:c See the discussion of the shuffle method in this section. # Section 11.14 The protected Data and Methods 59. A class design requires that a particular member variable must be accessible by any subclasses of this class, but file:///C|/Users/usuller/Downloads/chapter11.txt[12/4/2019 3:47:54 PM]

otherwise not by classes which are not members of the same package. What should be done to achieve this? a. The variable should be marked public. b. The variable should be marked private. c. The variable should be marked protected. d. The variable should have no special access modifier. e. The variable should be marked private and an accessor method provided. Key:c See Table 11.2. # 61. Which statements are most accurate regarding the following classes? class A { private int i; protected int j; } class B extends A { private int k; protected int m; } a. An object of B contains data fields i, j, k, m. b. An object of B contains data fields j, k, m. c. An object of B contains data fields j, m. d. An object of B contains data fields k, m. Key:a The data fields in a superclass are contained in a subclass. Whether the data fields in a superclass can be accessed in a subclass is a visibility issue. A private data field in a superclass cannot be directly accessed in a subclass, but the data field may have the getter or setter methods, which can be used to get or set a data field value. # 62. Which statements are most accurate regarding the following classes? class A { private int i; protected int j; } class B extends A { private int k; protected int m; // some methods omitted } a. In the class B, an instance method can only access i, j, k, m. b. In the class B, an instance method can only access j, k, m. c. In the class B, an instance method can only access j, m. d. In the class B, an instance method can only access k, m. Key:b See Table 11.2. # 60. Which of the following statements is false? a. A public class can be accessed by a class from a different package. b. A private method cannot be accessed by a class in a different package. file:///C|/Users/usuller/Downloads/chapter11.txt[12/4/2019 3:47:54 PM]

c. A protected method can be accessed by a subclass in a different package. d. A method with no visibility modifier can be accessed by a class in a different package. Key:d See Table 11.2. # 56. What modifier should you use on a class so that a class in the same package can access it but a class (including a subclass) in a different package cannot access it? a. public b. private c. protected d. Use the default modifier. Key:d See Table 11.2. # 57. What modifier should you use on the members of a class so that they are not accessible to another class in a different package, but are accessible to any subclasses in any package? a. public b. private c. protected d. Use the default modifier. Key:c See Table 11.2. # 58. The visibility of these modifiers increases in this order: a. private, protected, none (if no modifier is used), and public. b. private, none (if no modifier is used), protected, and public. c. none (if no modifier is used), private, protected, and public. d. none (if no modifier is used), protected, private, and public. Key:b See Table 11.2. # Section 11.15 Preventing Extending and Overriding 63. Which of the following classes cannot be extended? a. class A { } b. class A {&nbsp;&nbsp; private A() {&nbsp;&nbsp;}} c. final class A { } d. class A {&nbsp;&nbsp; protected A() {&nbsp;&nbsp;}} Key:c See the Key Point.

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Chapter 12 Exception Handling and Text I/O Section 12.2 Exception-Handling Overview 5. The following code causes Java to throw

int number = Integer.MAX_VALUE + 1; a. RuntimeException b. Exception c. Error d. Throwable e. no exceptions Key:e At present, Java does not throw integer overflow exceptions. The future version of Java may fix this problem to throw an overflow exception. # 7. What exception type does the following program throw? public class Test { public static void main(String[] args) { System.out.println(1 / 0); } } a. ArithmeticException b. ArrayIndexOutOfBoundsException c. StringIndexOutOfBoundsException d. ClassCastException e. No exception Key:a Integer division by 0 throws ArithmeticException. # Section 12.3 Exception Types 1. A Java exception is an instance of a. RuntimeException b. Exception c. Error d. Throwable e. NumberFormatException Key:d See Figure 12.1.

# 2. An instance of describes system errors. If this type of error occurs, there is little you can do beyond notifying the user and trying to terminate the program gracefully. a. RuntimeException b. Exception c. Error d. Throwable e. NumberFormatException Key:c See the bullet items. # 3. An instance of describes the errors caused by your program and external circumstances. These errors can be caught and handled by your program. a. RuntimeException ..

b. Exception c. Error d. Throwable e. NumberFormatException Key:b See the bullet items. # 6. Instances of are unchecked exceptions. a. RuntimeException b. Exception c. Error d. Throwable e. NumberFormatException Key:ace NumberFormatException is a subclass of RuntimeException # 8. What exception type does the following program throw? public class Test { public static void main(String[] args) { int[] list = new int[5]; System.out.println(list[5]); } } a. ArithmeticException b. ArrayIndexOutOfBoundsException c. StringIndexOutOfBoundsException d. ClassCastException e. No exception Key:b The array size is 5. list[5] causes ArrayIndexOutOfBoundsException. # 9. What exception type does the following program throw? public class Test { public static void main(String[] args) { String s = "abc"; System.out.println(s.charAt(3)); } } a. ArithmeticException b. ArrayIndexOutOfBoundsException c. StringIndexOutOfBoundsException d. ClassCastException e. No exception Key:c The array size is 3. s.charAt(3) causes ArrayIndexOutOfBoundsException. # Section 12.4 Declaring, Throwing, and Catching Exceptions Section 12.4.1 Declaring Exceptions 13. A method must declare to throw . a. unchecked exceptions b. checked exceptions c. Error © 2020 Pearson Education, Inc., Hoboken, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist.

d. RuntimeException Key:b See th end of Section 12.3. # 11. What exception type does the following program throw? public class Test { public static void main(String[] args) { Object o = null; System.out.println(o.toString()); } } a. ArithmeticException b. ArrayIndexOutOfBoundsException c. StringIndexOutOfBoundsException d. ClassCastException e. NullPointerException Key:e See Figure 12.1 in Section 12.3. # 12. What exception type does the following program throw? public class Test { public static void main(String[] args) { Object o = null; System.out.println(o); } } a. ArithmeticException b. ArrayIndexOutOfBoundsException c. StringIndexOutOfBoundsException d. No exception e. NullPointerException Key:d The code is fine. No errors. # Section 12.4.2 Throwing Exceptions 14. Which of the following statements are true? a. You use the keyword throws to declare exceptions in the method heading. b. A method may declare to throw multiple exceptions. c. To throw an exception, use the key word throw. d. If a checked exception occurs in a method, it must be either caught or declared to be thrown from the method. Key:abcd All these statements are true. # 15. Analyze the following code: public class Test { public static void main(String[] args) throws MyException { System.out.println("Welcome to Java"); } } class MyException extends Error { ..

} a. You should not declare a class that extends Error, because Error raises a fatal error that terminates the program. b. You cannot declare an exception in the main method. c. You declared an exception in the main method, but you did not throw it. d. The program has a compile error. Key:a When an exception of Error type occurs, your program would terminate. Therefore, you should not declare an exception that extends Error. You declared an exception in the main method. If you did not throw anything, that is fine. # 10. What exception type does the following program throw? public class Test { public static void main(String[] args) { Object o = new Object(); String d = (String)o; } } a. ArithmeticException b. ArrayIndexOutOfBoundsException c. StringIndexOutOfBoundsException d. ClassCastException e. No exception Key:d The object o is of the type Object. It cannot be cast to (String). # Section 12.4.3 Catching Exceptions 16. Analyze the following code: public class Test { public static void main(String[] args) { try { String s = "5.6"; Integer.parseInt(s); // Cause a NumberFormatException int i = 0; int y = 2 / i; } catch (Exception ex) { System.out.println("NumberFormatException"); } catch (RuntimeException ex) { System.out.println("RuntimeException"); } } } a. The program displays NumberFormatException. b. The program displays RuntimeException. c. The program displays NumberFormatException followed by RuntimeException. d. The program has a compile error. Key:d catch (RuntimeException ex) should be specified before catch (Exception ex). # 4. An instance of and numeric errors. ..

describes programming errors, such as bad casting, accessing an out-of-bounds array,

a. RuntimeException b. Exception c. Error d. Throwable e. NumberFormatException Key:a See Table 12.3 in Section 12.3. # Section 12.4.4 Getting Information from Exceptions 17. Analyze the following program. public class Test { public static void main(String[] args) { try { String s = "5.6"; Integer.parseInt(s); // Cause a NumberFormatException int i = 0; int y = 2 / i; System.out.println("Welcome to Java"); } catch (Exception ex) { System.out.println(ex); } } } a. An exception is raised due to Integer.parseInt(s); b. An exception is raised due to 2 / i; c. The program has a compile error. d. The program compiles and runs without exceptions. Key:a Both (A) and (B) would cause exception, but (A) occurred first, so the exception is due to (A). # 18.