Question 1

These are Java programs that are usually part of a Web site.

Accepted Answer

Applets are Java programs that run within a Web browser, typically used for interactive features on a Web page.

Question 2

A mouse motion listener class can respond to:

Accepted Answer

The mouse moved event is generated when the mouse cursor is moved within a component's screen space.

Question 3

If a frame component is 300 pixels wide and 200 pixels high, the upper, right-hand corner has (X, Y) coordinates of:

Accepted Answer

In a Cartesian coordinate system, the x-coordinate represents the horizontal position and starts at 0 on the left-hand side of the frame. The y-coordinate represents the vertical position and starts at 0 at the bottom of the frame. 
Therefore, the upper, right-hand corner would have an x-coordinate of 299 (300-1 because the frame component starts at 0) and a y-coordinate of 0. 
Option D is the only choice that has the correct x-coordinate.

Question 4

What will happen if you use instead of in an HTML document?

Accepted Answer

HTML is not case-sensitive for tag names, so will work the same as , centering the text.

Question 5

Look at the following applet code:
1 import javax.swing.*;
2 import java.awt.*;
3 public class GraphicsTest extends JApplet
4 {
5 public void init()
6 {
7 getContentPane().setBackground(Color.WHITE);
8 }
9 public void paint(Graphics g)
10 {
11 super.paint(g);
12 g.setColor(Color.YELLOW);
13 g.fillOval(100, 100, 50, 50);
14 g.setColor(Color.BLACK);
15 g.setFont(new Font("SansSerif", Font.BOLD, 35));
16 g.drawString("SLOW", 110, 110);
17 }
18 }
What shape will the oval have?

Accepted Answer

The oval will be a circle with a width and height of 50 pixels. This is because the parameters for the fillOval() method specify starting coordinates for the top left corner of a rectangle that bounds the circle, as well as the width and height of that rectangle. Since the width and height are both set to 50 pixels, the oval will be a perfect circle.

Question 6

An applet using a Swing GUI is extended from this class.

Accepted Answer

To create applets using a Swing GUI, we need to extend the JApplet class. The other options do not provide the necessary functionality for creating applets. JFrame is a top-level container for creating standalone desktop applications, JLabel is a component for displaying text or images, and JSwing is not a built-in class in Java.

Question 7

What does the HTML tag <hr /> cause to happen?

Accepted Answer

The HTML tag <hr /> creates a horizontal line, also known as a horizontal rule.

Question 8

To support the Swing classes in applets, some browsers require a ________, which is software that extends or enhances another program.

Accepted Answer

Browsers require a plug-in to support the Swing classes in applets, as a plug-in is software that extends or enhances another program.

Question 9

Look at the following applet code:
1 import javax.swing.*;
2 import java.awt.*;
3 public class GraphicsTest extends JApplet
4 {
5 public void init()
6 {
7 getContentPane().setBackground(Color.WHITE);
8 }
9 public void paint(Graphics g)
10 {
11 super.paint(g);
12 g.setColor(Color.YELLOW);
13 g.fillOval(100, 100, 50, 50);
14 g.setColor(Color.BLACK);
15 g.setFont(new Font("SansSerif", Font.BOLD, 35));
16 g.drawString("SLOW", 110, 110);
17 }
18 }
Which line sets the color that will be used to draw "SLOW"?

Accepted Answer

Line 14 sets the color to BLACK, which is used to draw the string "SLOW" on the applet.

Question 10

Which of the following can a mouse listener respond to?

Accepted Answer

A mouse listener can respond to when the mouse button is pressed (MouseListener.mousePressed), when the mouse button is clicked (MouseListener.mouseClicked), and when the mouse cursor enters a component's screen space (MouseListener.mouseEntered). Therefore, all of the above options are valid for a mouse listener to respond to.

Question 11

When you extend an interface, you must implement all the methods defined in the interface. If you are interested in only one or two mouse events, you can extend the ________ class which implements the MouseListener interface, but does not require you to write all the functions in the interface.

Accepted Answer

The MouseAdapter class implements the MouseListener interface, but provides default implementations for all the methods. This allows the programmer to only implement the methods they are interested in instead of having to implement all the methods in the interface.

Question 12

In an applet, events are handled:

Accepted Answer

Events in applets are handled with event listeners, which work in the same way as they do in GUI applications. Therefore, option C is correct. Option A is partially correct since event listeners used in GUI applications can also be used in applets. Option B is incorrect because event handling does not depend on the computer running the applet. Option D is also incorrect since events do not always result in terminating the applet.

Question 13

If an applet attempts to violate one of the JVM restrictions:

Accepted Answer

When an applet attempts to violate one of the JVM restrictions, Java Virtual Machine will throw an exception indicating which restriction has been violated. The applet will then stop executing and the exception will be reported to the Java console.

Question 14

Given the following code, how many times per second will the TimerListener event be generated?
Timer timer = new Timer(1000, new TimerListener());

Accepted Answer

The Timer class is configured with a delay of 1000 milliseconds, which means it will fire an event once every 1000 milliseconds or 1 second. Therefore, the TimerListener event will be generated once per second.

Question 15

Which of the following sound file formats does Java not support?

Accepted Answer

Java supports all of the listed sound file formats: .wav, .au, and .mid.

Question 16

One way of viewing the results of the applet which is invoked in the HTML document TestApplet.html is to enter the following at the command prompt.

Accepted Answer

The correct command to view the applet is "appletviewer" followed by the HTML document name, which in this case is TestApplet.html. Therefore, the correct command is "appletviewer TestApplet.html". The other options are not valid commands and will not display the results of the applet.

Question 17

In the following code that uses a Swing GUI, which line has an error?
1 public class TestApplet extends Applet
2 {
3 public void init()
4 {
5 JLabel label = new JLabel("Test label");
6 setLayout(new FlowLayout());
7 add(label);
8 }
9 }

Accepted Answer

The correct answer is A because the class TestApplet extends Applet, which is not a Swing component. To use Swing components, the class should extend javax.swing.JApplet.

Question 18

Look at the following applet code:
1 import javax.swing.*;
2 import java.awt.*;
3 public class GraphicsTest extends JApplet
4 {
5 public void init()
6 {
7 getContentPane().setBackground(Color.WHITE);
8 }
9 public void paint(Graphics g)
10 {
11 super.paint(g);
12 g.setColor(Color.YELLOW);
13 g.fillOval(100, 100, 50, 50);
14 g.setColor(Color.BLACK);
15 g.setFont(new Font("SansSerif", Font.BOLD, 35));
16 g.drawString("SLOW", 110, 110);
17 }
18 }
What will be the coordinates of the center of the oval?

Accepted Answer

The oval is drawn with a starting position of (100, 100) and a width of 50 and height of 50. The center of the oval will be at (100 + 25, 100 + 25), which is (125, 125).

Question 19

The ________ object is responsible for drawing the entire applet window.

Accepted Answer

The Graphics object is responsible for drawing the entire applet window, as it provides the necessary methods to render shapes, text, and images on the screen.

Question 20

Hypertext can contain:

Accepted Answer

Hypertext can contain a link to another web page, allowing users to navigate and access various information on the internet. However, it cannot contain executable code, exception methods or a Java application program, as those are programming elements that require a specific platform or language to run.

Quiz 14: Applets and More