— Scott McNealy, Sun Microsystems Chairman, President and ceo

360
 
chapter 12
import javax.swing.*;
import java.awt.event.*;
public class SimpleGui1B
 implements ActionListener {

JButton button;

 public static void main (String[] args) {
SimpleGui1B gui = new SimpleGui1B();
gui.go();
}

 public void go() {

JFrame frame = new JFrame();
button = new JButton(“click me”);
button.addActionListener(this);

frame.getContentPane().add(button);

frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(300,300);
frame.setVisible(true);

}
public void actionPerformed(ActionEvent event) {
button.setText(“I’ve been clicked!”);
}
}
Implement the interface. This says, 
“an instance of SimpleGui1B IS-A 
ActionListener”.
(The button 
will give events 
only to 
ActionListener implementers)
register your interest with the button. This says 
to the button, “Add me to your list of listeners”. 
The argument you pass MUST be an object from a 
class that implements ActionListener
!!
a new import statement 
for the package that 
ActionListener and ActionEvent are in.
Implement the ActionListener 
interface’s 
actionPerformed() method.. This is the 
actual event-handling method!
The button calls this method to let you know an event 
happened. It sends you an ActionEvent object as the 
argument, but we don’t need it. Knowing the event
happened is enough info for us.
2
3
1
Implement the ActionListener interface
1
Register with the button (tell it you 
want to listen for events)