Graphical user interfaces - Data Structures and Problem Solving Using Java - page 951

figure B.13
CloseableFrame class
using WindowAdapter
and inner class

1 // Frame that closes on a window-close event: (works!)
2 public class CloseableFrame extends JFrame
3 {
4 public CloseableFrame( )
5 { addWindowListener( new ExitOnClose( ) ); }
6
7 private class ExitOnClose extends WindowAdapter
8 {
9 public void windowClosing( WindowEvent event )
10 { System.exit( 0 ); }
11 }
12 }

figure B.14
CloseableFrame class
using WindowAdapter
and anonymous inner
class

1 // Frame that closes on a window-close event: (works!)
2 public class CloseableFrame extends JFrame
3 {
4 public CloseableFrame( )
5 {
6 addWindowListener( new WindowAdapter( )
7 {
8 public void windowClosing( WindowEvent event )
9 { System.exit( 0 ); }
10 }
11 );
12 }
13 }

is horrific, but experienced readers of Java code skip over those syntactic
details and easily see what the event-handling code does. The main benefit
here is that if there are lots of small event-handling methods, they need not be
scattered in top-level classes but instead can be placed near the objects that
these events are coming from.

B.3.5 summary: putting the pieces together

Here is a summary of how to create a GUI application. Place the GUI func-
tionality in a class that extends JPanel . For that class, do the following:

1. Decide on the basic input elements and text output elements. If the

same elements are used twice, make an extra class to store the com-
mon functionality and apply these principles on that class.