Finals Study Guide (Multiple Choice Section)

Question 1

Which of the following statements is correct to display Welcome to Java on the console? (Choose all that apply.)

Answer 1

System.out.println(“Welcome to Java”);

System.out.print(“Welcome to Java”);

Question 2

________ is the brain of a computer.

Answer 2

CPU

Question 3

Every letter in a Java keyword is in lowercase.

Answer 3

false

Question 4

To declare a constant MAX_LENGTH inside a method with value 99.98, you write

Answer 4

final double MAX_LENGTH = 99.98;

Question 5

________ is the physical aspect of the computer that can be seen.

Answer 5

Hardware

Question 6

________is interpreted.

Answer 6

Java

Question 7

Which of the following assignment statements is incorrect? (Choose all that apply.)

Answer 7

i = 1 = j = 1 = k = 1;
i = 1; j = 1; k = 1;
i == j == k == 1;

Question 8

A block is enclosed inside ________.

Answer 8

braces

Question 9

The main method header is written as:

Answer 9

public static void main(String[ ] args)

Question 10

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);
     }
}

Answer 10

2.0

Question 11

________ is the Java assignment operator.

Answer 11

=

Question 12

________ are instructions to the computer. (Choose two.)

Answer 12

Programs

Software

Question 13

Which of the following are correct ways to declare variables? (Choose two.)

Answer 13

int length, width;

int length; int width;

Question 14

Which of the following is a valid identifier? (Choose all that apply.)

Answer 14

class
$343
radius

Question 15

Suppose you define a Java class as follows:

public class Test {

}

In order to compile this program, the source code should be stored in a file named

Answer 15

Test.java

Question 16

One byte has ________ bits.

Answer 16

8

Question 17

To assign a value 1 to variable x, you write

Answer 17

x = 1;

Question 18

Every statement in Java ends with ________.

Answer 18

a semicolon (;)

Question 19

Which of the following are correct names for variables according to Java naming conventions? (Choose all that apply.)

Answer 19

radius

findArea

Question 20

Suppose a Scanner object is created as follows:

Scanner input = new Scanner(System.in);

What method do you use to read an int value?

Answer 20

input.nextInt();

Question 21

What is 1 + 1 + 1 + 1 + 1 == 5?

Answer 21

true

Question 22

What is the printout of the following switch statement?
char ch = 'a';
switch (ch) {
     case 'a':
     case 'A':
          System.out.print(ch); break;
     case 'b':
     case 'B':
          System.out.print(ch); break;
     case 'c':
     case 'C':
          System.out.print(ch); break;
     case 'd':
     case 'D':
          System.out.print(ch);
}

Answer 22

a

Question 23

What is the printout of the following switch statement?

char ch = ‘b’;

switch (ch) {
     case 'a':
          System.out.print(ch);
     case 'b':
          System.out.print(ch);
     case 'c':
          System.out.print(ch);
     case 'd':
          System.out.print(ch);
}

Answer 23

bbb

Question 24

Analyze the following code:

if (x < 100) && (x > 10)
System.out.println(“x is between 10 and 100”);

Answer 24

The statement has compile errors because (x 10) must be enclosed inside parentheses.

Question 25

The equal comparison operator in Java is ________.

Answer 25

==

Question 26

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");

}

Answer 26

Income is greater than 3000

Question 27

Analyze the following code.

boolean even = false;
if (even) {
System.out.println(“It is even!”);
}

Answer 27

The code displays nothing.

Question 28

Which of the following code displays the area of a circle if the radius is strictly positive?

Answer 28

if (radius > 0) System.out.println(radius * radius * 3.14159);

Question 29

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?

Answer 29

((x < 100) && (x > 1)) || (x < 0)

Question 30

In Java, the word true is ________.

Answer 30

a Boolean literal

Question 31

The following code displays ________.

double temperature = 50;

if (temperature >= 100)
     System.out.println("too hot");
else if (temperature );

Answer 31

just right

Question 32

Suppose x = 1, y = -1, and z = 1. What is the printout of the following statement?

if (x > 0)
     if (y > 0)
          System.out.println("x > 0 and y > 0");
else if (z > 0)
     System.out.println("x  0");

Answer 32

x 0;

Question 33

Which of the Boolean expressions below is incorrect? (Choose three.)

Answer 33

(x != 0) || (x = 0)
(true) && (3 => 4)
(-10 < x < 0)

Question 34

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

int count = 0;
while (count < 10) {
     System.out.println("Welcome to Java");
     count++;
}

Answer 34

10

Question 35

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

(I):
for (int i = 0; i<10; i++) {
sum += i;
}

Answer 35

Yes

Question 36

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);

Answer 36

10

Question 37

What is the output for y?

int sum = 0;
for (int i = 0; i<10; ++i) {
     sum += i;  
}
System.out.println(sum);

Answer 37

45

Question 38

(char)(‘a’ + Math.random() * (‘z’ - ‘a’ + 1)) returns a random character ________.

Answer 38

between ‘a’ and ‘z’

Question 39

A variable defined inside a method is referred to as ________.

Answer 39

a local variable

Question 40

All Java applications must have a method ________.

Answer 40

public static void main(String[ ] args)

Question 41

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;
     }
}

Answer 41

The program displays long followed by 5.

Question 42

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;
 } }

Answer 42

The program displays int, long followed by 5.

Question 43

Arguments to methods always appear within ________.

Answer 43

parentheses

Question 44

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

public static void main(String[ ] args) {
Math.pow(2, 4);
}

Answer 44

No

Question 45

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;
}

Answer 45

No

Question 46

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.

Answer 46

a stack

Question 47

Given the following method

static void nPrint(String message, int n) {
     while (n > 0) {
          System.out.print(message);
          n--;
     }
}

What is the printout of the call nPrint(‘a’, 4)?

Answer 47

invalid call

Question 48

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);

Answer 48

2

Question 49

Suppose your method does not return any value, which of the following keywords can be used as a return type?

Answer 49

void

Question 50

The client can use a method without knowing how it is implemented. The details of the implementation are encapsulated in the method and hidden from the client who invokes the method. This is known as ________. (Choose all that apply.)

Answer 50

information hiding

Question 51

The signature of a method consists of ________.

Answer 51

method name and parameter list

Question 52

What is k after the following block executes?

{
     int k = 2;
     nPrint("A message", k);
}
System.out.println(k);

Answer 52

k is not defined outside the block. So, the program has a compile error

Question 53

When you invoke a method with a parameter, the value of the argument is passed to the parameter. This is referred to as ________.

Answer 53

pass by value

Question 54

Which of the following is a possible output from invoking Math.random()? (Choose all that apply.)

Answer 54

0. 5

0. 0

Question 55

Which of the following should be declared as a void method?

Answer 55

Write a method that prints integers from 1 to 100.

Question 56

A method that is associated with an individual object is called ________.

Answer 56

a class instance

Question 57

An object is an instance of a ________.

Answer 57

class

Question 58

Analyze the following code.

class Test {  
     public static void main(String[ ] args) { 
          String s;
          System.out.println("s is " + s);
     }
}

Answer 58

The program has a compilation error because s is not initialized, but it is referenced in the println statement.

Question 59

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);
     }
}

Answer 59

The program has a compile error because Test does not have a default constructor.

Question 60

Given the declaration Circle x = new Circle(), which of the following statement is most accurate?

Answer 60

x contains a reference to a Circle object.

Question 61

Given the declaration Circle[ ] x = new Circle[10], which of the following statement is most accurate?

Answer 61

x contains a reference to an array and each element in the array can hold a reference to a Circle object.

Question 62

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);

Answer 62

Nothing will be assigned to x, because the execution causes the runtime error StringIndexOutofBoundsException.

Question 63

The keyword ________ is required to declare a class.

Answer 63

class

Question 64

What is displayed by the following code?

public static void main(String[ ] args) throws Exception {
String[ ] tokens = “Welcome to Java”.split(“o”);
for (int i = 0; i

Answer 64

Welc me t Java

Question 65

What is the output of the following code?

String s = “University”;
s.replace(“i”, “ABC”);
System.out.println(s);

Answer 65

University

Question 66

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");
 } }

Answer 66

s1 and s2 reference to the same String object

Question 67

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");
 } }

Answer 67

s1 and s2 reference to different String objects

Question 68

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");
 } }

Answer 68

s1 and s2 have the same contents

Question 69

What is wrong in 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);
     }
}

Answer 69

The program has a compilation error because TempClass does not have a constructor with an int argument.

Question 70

When invoking a method with an object argument, ________ is passed.

Answer 70

the reference of the object

Question 71

Which of the following statements is most accurate? (Choose two.)

Answer 71

A reference variable refers to an object.

An object may contain the references of other objects.

Question 72

Which of the following statements is preferred to create a string “Welcome to Java”?

Answer 72

String s = “Welcome to Java”;

Question 73

________ is a construct that defines objects of the same type.

Answer 73

A class

Question 74

________ is invoked to create an object.

Answer 74

A constructor

Question 75

________ represents an entity in the real world that can be distinctly identified.

Answer 75

An object

Question 76

You can declare two variables with the same name in ________.

Answer 76

different methods in a class

Question 77

Object-oriented programming allows you to derive new classes from existing classes. This is called ________.

Answer 77

inheritance

Question 78

Which of the following statements are true? (Choose two.)

Answer 78

A subclass is usually extended to contain more functions and more detailed information than its superclass.

“class A extends B” means A is a subclass of B.

Question 79

Suppose you create a class Cylinder to be a subclass of Circle. Analyze the following code:

class Cylinder extends Circle {
    double length;

Cylinder(double radius) {
     Circle(radius);
} }

Answer 79

The program has a compile error because you attempted to invoke the Circle class’s constructor illegally.

Question 80

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");
    }
}

public class C {
    public static void main(String[ ] args) {
         B b = new B();
    }
}

Answer 80

“The default constructor of A is invoked”“The default constructor of B is invoked”

Question 81

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; 
} }

class B extends A {
    public void m(String s) {
    }
}

Answer 81

The method m is not overridden in B. B inherits the method m from A and defines an overloaded method m in B.

Question 82

Given the following code, find the compile error. (Choose two.)

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 {
    public String toString() {
         return "Student";
    }
}

class Person extends Object {
    public String toString() {
         return "Person";
    }
}

Answer 82

m(new Person()) causes an error

m(new Object()) causes an error

Question 83

Analyze the following code: (Choose two.)

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;
    public String toString() {
         return "A's x is " + x;
    }
}

Answer 83

When executing System.out.println(a2), the toString() method in the Object class is invoked.

When executing System.out.println(a1), the toString() method in the A class is invoked.