GUI BASICS - Introduction to Java Programming - page 469

JButton inherits AbstractButton and provides several constructors to create buttons,
as shown in Figure 12.16.

javax.swing.AbstractButton

javax.swing.JButton

+JButton()
+JButton(icon: javax.swing.Icon)
+JButton(text: String)
+JButton(text: String, icon: Icon)

Creates a default button without any text or icons.
Creates a button with an icon.
Creates a button with text.
Creates a button with text and an icon.

F IGURE 12.16

JButton defines a regular push button.

12.11.1 Icons, Pressed Icons, and Rollover Icons
A button has a default icon, a pressed icon, and a rollover icon. Normally you use the
default icon, because the other icons are for special effects. A pressed icon is displayed
when a button is pressed, and a rollover icon is displayed when the mouse is over the but-
ton but not pressed. For example, Listing 12.9 displays the U.S. flag as a regular icon,
the Canadian flag as a pressed icon, and the British flag as a rollover icon, as shown in
Figure 12.17.

L ISTING 12.9 TestButtonIcons.java
1 import javax.swing.*;
2
3 public class TestButtonIcons extends JFrame {
4 public static void main(String[] args) {
5 // Create a frame and set its properties
6 JFrame frame = new TestButtonIcons();
7 frame.setTitle( "ButtonIcons" );
8 frame.setSize( 200 , 100 );
9 frame.setLocationRelativeTo( null ); // Center the frame
10 frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
11 frame.setVisible( true );
12 }
13
14 public TestButtonIcons() {
15 ImageIcon usIcon = new ImageIcon( "image/usIcon.gif" );
16 ImageIcon caIcon = new ImageIcon( "image/caIcon.gif" );
17 ImageIcon ukIcon = new ImageIcon( "image/ukIcon.gif" );
18
19 JButton jbt = new JButton( "Click it" , usIcon);
20 jbt.setPressedIcon(caIcon);
21 jbt.setRolloverIcon(ukIcon);
22
23 add(jbt);
24 }
25 }

create icons

regular icon
pressed icon
rollover icon

add a button

(a) Default icon (b) Pressed icon (c) Rollover icon

F IGURE 12.17

A button can have several types of icons.