Question 21 Which one of the following is used in Java programming...

Question 21

Which one of the following is used in Java programming to handle asynchronous events?

Select one:

a. constructors

b. event handlers

c. overloading

d. pragmatics

e. protocols

Question 22

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 starts on line 1?

Select one:

a. a statement

b. a package

c. a method definition

d. a comment

e. a class definition

Question 23

Which of the following keywords is useful for skipping to the next iteration of a loop?

Select one:

a. break

b. case

c. continue

d. extends

e. switch

Question 24

What is the output of the following Java program?

interface Food {

  public void printFlavor();

}

class Pepper implements Food {

  public void printFlavor() { System.out.println("spicy"); }

}

public class Lunch {

  public static void main(String[] args) {

    Food pepper = new Pepper();

    pepper.printFlavor();

  }

}

Select one:

a. bland

b. bland

spicy

c. (no output)

d. spicy

e. the program does not compile

bland

Question 25

A subclass will ___ from its superclasses.

Select one:

a. extend

b. implement

c. inherit

d. overload

e. override

Question 26

Consider the following Java program. Which line implements an interface method?

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(); }

}

Select one:

a. addMouseListener(this);

b. public class MouseWhisperer extends JFrame implements MouseListener {

c. public static void main(String[] args) { new MouseWhisperer(); }

d. public void mouseEntered(MouseEvent e) { setTitle("I SEE YOU"); }

e. setVisible(true);

Question 27

Which one of the following does NOT describe an array?

Select one:

a. Its elements can be a primitive type.

b. The number of its elements can change.

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

d. It has a numbered sequence of elements.

e. It provides efficient random access to its elements.

Question 28

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 starts on line 3?

Select one:

a. a statement

b. a package

c. a method definition

d. a comment

e. a class definition

Question 29

What is the output of the following Java program?

public class Food {

  static int count;

  private String flavor = "sweet";

  Food(String s) { flavor = s; }

  void setFlavor(String s) { flavor = s; }

  String getFlavor() { return flavor; }

  static public void main(String[] args) {

    Food pepper = new Food("spicy");

    System.out.println(pepper.getFlavor());

  }

}

Select one:

a. false

b. smoky

c. spicy

d. sweet

e. true

Question 30

Which of the following can a class NOT be used for?

Select one:

a. a primitive type

b. a container for static methods

c. a container for static variables

d. a type for method parameters

e. a type for variables