Question

1) Consider the following Java program:

1 public class HelloWorld {
2     // My first program!
3     public static void main(String[] args) {
4         System.out.println("Hello, World!");
5     }
6 }

What is on line 1?

a. a variable declaration

b. a statement

c. a method (subroutine) definition

d. a comment

e. a class definition

2) Which one of the following does NOT describe an array?

a. It can be used in a for-each loop.

b. It has a numbered sequence of elements.

c. It provides efficient random access to its elements.

d. Its elements can be a primitive type.

e. The number of its elements can change.

3) What is the output of the following Java program?

abstract class Food {
    abstract void printFlavor();
}
class Pepper extends Food {
    void printFlavor() { System.out.println("spicy"); }
}
public class Lunch {
    public static void main(String[] args) {
        Food pepper = new Food();
        pepper.printFlavor();
    }
}

a. bland

b. bland
spicy

c. no output

d. spicy

e. the program does not compile

4) Which one of the following claims about Java is INCORRECT?

a. A class is a type.

b. An object belongs to a class.

c. An object is an instance of a class.

d. An object is a type.

e. "Object" is a class.

5) Consider the following Java program. Which statement updates the appearance of a button?

import java.awt.event.*;
import javax.swing.*;
public class Clicker extends JFrame implements ActionListener {
    int count;
    JButton button;
    Clicker() {
        super("Click Me");
        button = new JButton(String.valueOf(count));
        add(button);
        button.addActionListener(this);
        setSize(200,100);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setVisible(true);
    }
    public void actionPerformed(ActionEvent e) {
        count++;
        button.setText(String.valueOf(count));
    }
    public static void main(String[] args) { new Clicker(); }
}

a. add(button);

b. button.addActionListener(this);

c. button.setText(String.valueOf(count));

d. setVisible(true);

e. super("Click Me");

6) What is the output of the following Java program?

import java.util.*;
class ArrayGames {
    public static void main(String[] args) {
        ArrayList<Integer> a = new ArrayList<Integer>();
        for (int i = 1; i <= 5; i++) a.add(i);
        Integer n = 3;
        a.remove(n);
        System.out.println(a.toString());
    }
}

a. [0, 1, 2, 4, 5]

b. [1, 2, 3, 4, 5]

c. [1, 2, 3, 5]

d. [1, 2, 4, 5]

e. [4, 5]

7) Consider the following block of Java code. How many times will it output "Hello"?

for (int i = 1; i < 10; i++)
{
    System.out.println("Hello");
}

a. 0

b. 1

c. 9

d. 10

e. Too many!

8) Which of the following keywords is useful for getting out of an infinite loop?

a. break

b. continue

c. do

d. switch

e. while

9) Consider the following Java program, which one of the following best describes "setFlavor"?

public class Food {
    static int count;
    private String flavor = "sweet";
    Food() { count++; }
    void setFlavor(String s) { flavor = s; }
    String getFlavor() { return flavor; }
    static public void main(String[] args) {
        Food pepper = new Food();
        System.out.println(pepper.getFlavor());
    }
}

a. a class variable

b. a constructor

c. a local object variable

d. an instance variable

e. a method

10) In a do-while loop, how many times does the continuation condition run (if the loop has no break, return, or System.exit calls)?

a. At least once, at the beginning of each iteration.

b. At least once, at the end of each iteration.

c. Exactly once.

d. Zero or more times, at the beginning of each iteration.

e. Zero or more times, at the end of each iteration.

11) Which one of the following is an event handler?

a. an event generator

b. an event listener

c. an event loop

d. an event method

e. java.awt.event

12) Consider the following Java program. Which one of the following is a package?
import java.awt.event.*;
import javax.swing.*;
public class MouseWhisperer extends JFrame implements MouseListener {
    MouseWhisperer() {
        super("COME CLOSER");
        setSize(300,100);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        addMouseListener(this);
        setVisible(true);
    }
    public void mouseClicked(MouseEvent e) { setTitle("OUCH"); }
    public void mousePressed(MouseEvent e) { setTitle("LET GO"); }
    public void mouseReleased(MouseEvent e) { setTitle("WHEW"); }
    public void mouseEntered(MouseEvent e) { setTitle("I SEE YOU"); }
    public void mouseExited(MouseEvent e) { setTitle("COME CLOSER"); }
    public static void main(String[] args) { new MouseWhisperer(); }
}

a. java.awt.event

b. JFrame

c. MouseEvent

d. MouseListener

e. this

13) Consider the following Java method. Which term best describes what this method computes?

static int doSomething(int[] a) {
    int b = a[0];
    for (int c : a) if (b > c) b = c;
    return b;
}

a. average

b. maximum

c. minimum

d. sum

e. transpose

14) Consider the following Java program, what starts on line 2?
1 public class HelloWorld {
2     // My first program!
3     public static void main(String[] args) {
4         System.out.println("Hello, World!");
5     }
6 }

a. a variable declaration

b. a statement

c. a method (subroutine) definition

d. a comment

e. a class definition

15) What is the output of the following Java program?
import java.util.*;
class ArrayGames {
    public static void main(String[] args) {
        int[] a = new int[5];
        System.out.println(Arrays.toString(a));
    }
}

a. null

b. [0, 0, 0, 0, 0]

c. [5, 5, 5, 5, 5]

d. [null, null, null, null, null]

e. No output. It throws an exception.

16) Consider the following class definition. Which variables can be used in the missing "println" expression on line 8?
1 public class PrintStuff
2 {
3      public static void main()
4      {
6          {
7              int i = -1;
8              System.out.println(_____);
9          }
10         int j = 1;
11         for (j = 0; j < 10; j++) {
12             System.out.println(_____);
13         }
14         {
15             int k;
16             for (k = 0; k < 10; k++) {
17                System.out.println(_____);
18             }
19         }
20        System.out.println(_____);
21     }
22 }

a. Only "i"

b. Only "j"

c. Only "k"

d. "i" and "j"

e. "j" and "k"

17) Consider the following Java statements.
int x = 3;
x = x++;

What is the value x is holding?

a. 0

b. 3

c. 4

d. 5

e. The question is moot. The statements have a syntax error.

18) Consider the following Java method. Which term best describes what this method computes?

static int doSomething(int[] a) {
    int b = 0;
    for (int c : a) b += c;
    return b;
}

a. average

b. maximum

c. minimum

d. sum

e. transpose

19) Consider the following Java method, which term best describes "'("Hello, World!")"?

public static void main(String[] args) {
    System.out.println("Hello, World!");
}

a. actual parameter or argument

b. formal parameter

c. method call

d. modifier

e. return type

20) Consider the following Java method, which term best describes "void"?
public static void main(String[] args) {
    System.out.println("Hello, World!");
}

a. actual parameter or argument

b. formal parameter

c. method call

d. modifier

e. return type

21) What is the output of the following Java program?
class Sum {
    static int sum = 0;
    static void add(int i) { sum += i; }
    public static void main(String[] args) {
        for (int i = 0; i < 10; i++) add(i);
        System.out.println(sum);
    }
}

a. 0

b. 9

c. 10

d. 45

e. 100

22) Consider the following Java program. Which object registers event listeners?
import java.awt.event.*;
import javax.swing.*;
public class MouseWhisperer extends JFrame implements MouseListener {
    MouseWhisperer() {
        super("COME CLOSER");
        setSize(300,100);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        addMouseListener(this);
        setVisible(true);
    }
    public void mouseClicked(MouseEvent e) { setTitle("OUCH"); }
    public void mousePressed(MouseEvent e) { setTitle("LET GO"); }
    public void mouseReleased(MouseEvent e) { setTitle("WHEW"); }
    public void mouseEntered(MouseEvent e) { setTitle("I SEE YOU"); }
    public void mouseExited(MouseEvent e) { setTitle("COME CLOSER"); }
    public static void main(String[] args) { new MouseWhisperer(); }
}

a. java.awt.event

b. JFrame

c. MouseEvent

d. MouseListener

e. this

23) What is the output of the following Java program?
class Food {
    Food() { printFlavor(); }
    void printFlavor() { System.out.println("bland"); }
}
class Pepper extends Food {
    void printFlavor() { System.out.println("spicy"); }
}
public class Lunch {
    public static void main(String[] args) {
        Food lunch = new Pepper();
    }
}

a. bland

b. bland
spicy

c. no output

d. spicy

e. the program does not compile

Answer 1

Answer 1: E
here we use class keyword to define the class
Wrong Answers:
A: for variable declaration we dont use class keyword
B: statement ends with ;
C: method definition we dont use class keyword
D: comments starts with // or /*

Answer 2: e. The number of its elements can change.
Size of the array is fixed so we ca't change it
Wrong Answers:
A: we can use array with for each
B: indexes starts from 0 to size-1
C: we can aaccess any element with index at constant time
Answer 3: e. the program does not compile
we can't create the instance for the abstract class
Answer 4:e. "Object" is a class.

an Object is not class it is instance of the class

As per policy we can answer 1 question per post. Please post the remianing questions as separate post.Thanks