Java Tutorial/Swing Event/Property Event

Using Property Change Listeners as Observers

   <source lang="java">

import java.awt.BorderLayout; import java.awt.Color; import java.awt.EventQueue; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import java.beans.PropertyChangeEvent; import java.beans.PropertyChangeListener; import java.util.Random; import javax.swing.JButton; import javax.swing.JFrame; public class PropertyChangeListenerDemo {

 public static void main(String args[]) {
   Runnable runner = new Runnable() {
     public void run() {
       JFrame frame = new JFrame("Button Sample");
       frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
       final JButton button1 = new JButton("Select Me");
       final JButton button2 = new JButton("No Select Me");
       final Random random = new Random();
       // Define ActionListener
       ActionListener actionListener = new ActionListener() {
         public void actionPerformed(ActionEvent actionEvent) {
           JButton button = (JButton) actionEvent.getSource();
           int red = random.nextInt(255);
           int green = random.nextInt(255);
           int blue = random.nextInt(255);
           button.setBackground(new Color(red, green, blue));
         }
       };
       // Define PropertyChangeListener
       PropertyChangeListener propertyChangeListener = new PropertyChangeListener() {
         public void propertyChange(PropertyChangeEvent propertyChangeEvent) {
           String property = propertyChangeEvent.getPropertyName();
           if ("background".equals(property)) {
             button2.setBackground((Color) propertyChangeEvent.getNewValue());
           }
         }
       };
       button1.addActionListener(actionListener);
       button1.addPropertyChangeListener(propertyChangeListener);
       button2.addActionListener(actionListener);
       frame.add(button1, BorderLayout.NORTH);
       frame.add(button2, BorderLayout.SOUTH);
       frame.setSize(300, 100);
       frame.setVisible(true);
     }
   };
   EventQueue.invokeLater(runner);
 }

}</source>