Graphical User Interfaces - Java - page 558

public public class class ButtonDemo2b ButtonDemo2b extends extends Applet {

Button b1 , b2 ;
ActionListener handler = new

new ButtonHandler ();

public public void void init () {

add ( b1 = new new Button ( "A button" ));

b1 . addActionListener ( handler );

add ( b2 = new new Button ( "Another button" ));

b2 . addActionListener ( handler );

}

class class ButtonHandler ButtonHandler implements implements ActionListener {

public public void void actionPerformed ( ActionEvent e ) {

iif ( e . getSource () == b1 )
showStatus ( "Thanks for pushing my first button!" );

else

showStatus ( "Thanks for pushing my second button!" );

}

}

}

Note that merely breaking the action handling code into its own class doesn't really contrib-
ute much to readability. But there is a way to use inner classes that does promote readability
and maintainability. We create an inner class (see Using Inner Classes ) for each event
source—each button, each menu item, and so on. Sounds like a lot of work, and it would be,
if you used the previous method. But there is a shorter way, using anonymous inner classes,
described next.

Action Handling Using Anonymous Inner Classes

Problem

You want action handling with less creation of special classes.

Solution

Use anonymous inner classes.