A+ Answers

Question 1

The method __________ sets the background color to yellow in JFrame frame.

Question 1 options:

setBackground(Color.YELLOW)

frame.setBackGround(Color.yellow)

setBackground(Color.yellow)

frame.setBackground(Color.YELLOW)

Question 2

What layout manager should you use so that every component occupies the same size in the container?

Question 2 options:

FlowLayout

any layout

BorderLayout

GridLayout

Question 3

Which of the following statements is for terminating the program when closing the frame?

Question 3 options:

frame.setDefaultCloseOperation(null)

frame.setDefaultCloseOperation(JFrame.TERMINATE_ON_CLOSE)

frame.setDefaultCloseOperation(JFrame.STOP_ON_CLOSE)

frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE)

Question 4

Which of the following statements about containers is correct?

Question 4 options:

Both frames and panels can be placed inside a panel

A panel can be placed inside a panel

A frame can be placed inside a panel

A frame can be placed inside a frame

Question 5

Which method call puts the string "Result" into the TextField named result?

Question 5 options:

result.findText()

result.text("Result")

result.newText("Result")

result.setText("Result")

Question 6

How many items can be added into a JComboBox object?

Question 6 options:

0

1

Unlimited

2

Question 7

What kind of object is used group radio buttons?

Question 7 options:

Group

ButtonGroup

JButtonGroup

ContainerGroup

Question 8  

Which of the following method calls is used to prevent the user from modifying a text field tf?

Question 8 options:

tf.setUneditable()

tf.setEditable(false);

tf.preventMdification()

tf.setChangable(false);

Question 9

When you want to allow the user to select only one of several choices, which you use?

Question 9 options:

Text fields

Ordinary buttons

Radio buttons

Check boxes

Question 10

What is the benefit of using layout managers?

Question 10 options:

It reduces the amount of code needed

It defines how components of a window should be arranged when it is resized

It makes the program run much faster

It reduces the amount of memory necessary to store the window components

Question 11

Which of the following true about source and listener objects?

Question 11 options:

Both objects must be of the same type

The objects must always be of different types

They must always be different objects

They can be the same object

Question 12

Which of the following statements is incorrect?

Question 12 options:

A listener may listen for multiple sources

The listener object's class must implement the corresponding event-listener interface

A source object can only have one listener object

The listener object must be registered by the source object

Question 13

Given the code below, indicate which statement describes its behavior.

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class Quiz3A extends JFrame implements ActionListener
{
   public Quiz3A()
   {
       JButton okButton = new JButton("OK");
       add(okButton);
   }

   public void actionPerformed(ActionEvent e)
   {
       System.out.println("The OK button is clicked");
   }

   public static void main(String[] args)
   {
       JFrame frame = new Quiz3A();
       frame.setSize(300, 300);
       frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
       frame.setVisible(true);
   }
}

Question 13 options:

The actionPerformed method is not executed when you click the OK button, because no instance of Quiz3A is registered with okButton

The program has a compilation error because no listeners are registered for okButton

The message The OK button is clicked is displayed when you click the OK button

The program has a runtime error because no listeners are registered with okButton

Question 14

The listener for an button event is an instance of ________.

Question 14 options:

KeyListener

ActionListener

MouseListener

ItemListener

Question 15

Which of the following statements registers a panel object aPanel as a listener for a button variable aButton?

Question 15 options:

aButton.addActionEventListener(aPanel);

addActionListener(aPanel);

aPanel.addEventListener(aPanel);

aButton.addActionListener(aPanel);

Question 16

In the program below, which object is listening for the events of okButton?

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class Quiz3B extends JFrame implements ActionListener
{
   private JButton okButton = new JButton("OK");

   public Quiz3B()
   {
       add(okButton);
       okButton.addActionListener(this);
   }

   public void actionPerformed(ActionEvent e)
   {
       System.out.println("The OK button is clicked");
   }

   public static void main(String[] args)
   {
       JFrame frame = new Quiz3B();
       frame.setSize(300, 300);
       frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
       frame.setVisible(true);
   }
}

okButton

An anonymous object

frame

JButton

Question 17

What is the benefit of using adapter classes rather than listeners interfaces?

Question 17 options:

It enables multiple inheritance of classes

It makes it unnecessary to implement unused event handling methods

It makes the response time for responding to events much quicker

It makes it possible to respond to several events at the same time

Question 18

In the program below, which object is listening for the events of okButton?

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class Quiz3C extends JFrame
{
   private JButton okButton = new JButton("OK");

   public Quiz3C()
   {
       add(okButton);
       okButton.addActionListener(
               new ActionListener()
               {
                   @Override
                   public void actionPerformed(ActionEvent ae)
                   {
                       System.out.println("The OK button is clicked");
                   }
               });
   }
   public static void main(String[] args)
   {
       JFrame frame = new Quiz3C();
       frame.setSize(300, 300);
       frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
       frame.setVisible(true);
   }
}

An anonymous object

frame

JButton

okButton

Question 19

Which of the following will occur if you fail to register an object as a listener for the click events of a button?

The containing frame will be considered as the default listener

A compilation error will occur

Nothing will happen when the button is clicked

A class cast exception will be thrown at run-time

Question 20

When a mouse event is generated how is the location of the click point determined?

The event handler must generate a secondary event to obtain the location

It is automatically saved as an instance variable in the object of which the mouse was clicked

It is obtained by calling a method of the mouse object

It is extracted from the mouse event that is passed to the event handler