//cd c:\JavaTry\MySwing
//javac ColorPane2.java
//set CLASSPATH=.	
//appletviewer ColorPane2.java

import java.applet.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

/*
    <applet code="ColorPane2.class" width=300 height=200>
    </applet>
*/

public class ColorPane2 extends JApplet {
     public void init(){
        Container contentPane = getContentPane();
        ColorPanel2 panel = new ColorPanel2();
        contentPane.add(panel);
    }
} 

class ColorPanel2 extends JPanel {
   JButton yellowB;
   JButton blueB;
   JButton redB;
 
   public ColorPanel2() {
      yellowB = new JButton("Yellow");
      blueB = new JButton("Blue");
      redB = new JButton("Red");
 
      add(yellowB);
      add(blueB);
      add(redB);

      yellowB.addActionListener(new Response());
      blueB.addActionListener(new Response());
      redB.addActionListener(new Response());
  }

 class Response implements ActionListener {
   public void actionPerformed(ActionEvent event) {
        Color c;
        Object source = event.getSource();
        if (source == yellowB) {
            c=Color.yellow;
        } else if  (source == blueB) {
            c=Color.blue;
        } else  {
            c=Color.red;
        }
        setBackground(c);
    }
 }
}

/*
   yellowB.addActionListener(this) などを 
   yellowB.addActionListener(new Response()) にお置き換える。
*/