Graphical user interfaces - Data Structures and Problem Solving Using Java - page 949

1 // Frame that closes on a window-close event
2
3 public class CloseableFrame extends JFrame
4 implements WindowListener
5 {
6 public CloseableFrame( )
7 { addWindowListener( this ); }
8
9 public void windowClosing( WindowEvent event )
10 { System.exit( 0 ); }
11 public void windowClosed( WindowEvent event )
12 { }
13 public void windowDeiconified( WindowEvent event )
14 { }
15 public void windowIconified( WindowEvent event )
16 { }
17 public void windowActivated( WindowEvent event )
18 { }
19 public void windowDeactivated( WindowEvent event )
20 { }
21 public void windowOpened( WindowEvent event )
22 { }
23 }

figure B.10
CloseableFrame class:
same as JFrame but
handles the window-
closing event

figure B.11
main routine for
Figure B.1

1 class BasicGUI extends CloseableFrame
2 {
3 public static void main( String [ ] args )
4 {
5 JFrame f = new BasicGUI( );
6 f.setTitle( "GUI Demo" );
7
8 Container contentPane = f.getContentPane( );
9 contentPane.add( new GUI( ) );
10 f.pack( );
11 f.show( );
12 }
13 }

B.3.4 event handling: adapters and
anonymous inner classes

The CloseableFrame class is a mess. To listen for a WindowEvent , we must declare
a class that implements the WindowListener interface, instantiate the class, and
then register that object with the CloseableFrame . Since the Window-Listener