Java Reference
In-Depth Information
Display 18.2
A Window Listener (part 1 of 3)
1 import javax.swing.JFrame;
2 import javax.swing.JPanel;
3 import java.awt.BorderLayout;
4 import java.awt.FlowLayout;
5 import java.awt.Color;
6 import javax.swing.JLabel;
7 import javax.swing.JButton;
8 import java.awt.event.ActionListener;
9 import java.awt.event.ActionEvent;
10 import java.awt.event.WindowListener;
11 import java.awt.event.WindowEvent;
12 public class WindowListenerDemo extends JFrame
13 {
14
public static final int WIDTH = 300; //for main window
15
public static final int HEIGHT = 200; //for main window
16
public static final int SMALL_WIDTH = 200; //for confirm window
17
public static final int SMALL_HEIGHT = 100; //for confirm window
18 private class CheckOnExit implements WindowListener
19 {
20 public void windowOpened(WindowEvent e)
21 {}
This WindowListener
class is an inner class.
22 public void windowClosing(WindowEvent e)
23 {
24 ConfirmWindow checkers = new ConfirmWindow();
25 checkers.setVisible( true );
26 }
27 public void windowClosed(WindowEvent e)
28 {}
29 public void windowIconified(WindowEvent e)
30 {}
31 public void windowDeiconified(WindowEvent e)
32 {}
A window listener must
define all the method
headings in the W indowListener
interface, even if some are trivial
implementations.
33 public void windowActivated(WindowEvent e)
34 {}
35 public void windowDeactivated(WindowEvent e)
36 {}
37 } //End of inner class CheckOnExit
38 private class ConfirmWindow extends JFrame implements
ActionListener
39 {
40 public ConfirmWindow()
41 {
42 setSize(SMALL_WIDTH, SMALL_HEIGHT);
43 getContentPane().setBackground(Color.YELLOW);
Another
(continued)
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