Java Tutorial/Swing Event/Property Event

Using Property Change Listeners as Observers

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);
  }
}