//example 7-22
import java.applet.Applet;
import java.awt.*;
import java.awt.event.*;
public class tt extends Applet implements ItemListener
{
   CheckboxGroup ColorGroup;
   Checkbox red,green,blue,yellow;
   Color color;
   public void init()
   {
   	 ColorGroup=new CheckboxGroup();
   	 color=Color.red;
   	 red=new Checkbox("Red",ColorGroup,true); 
   	 red.addItemListener(this);
   	 add(red);
   	 green=new Checkbox("Green",ColorGroup,false); 
   	 green.addItemListener(this);
   	 add(green);
   	 blue=new Checkbox("Blue",ColorGroup,false); 
   	 blue.addItemListener(this);
   	 add(blue);
   	 yellow=new Checkbox("Yellow",ColorGroup,false); 
   	 yellow.addItemListener(this);
   	 add(yellow);
   }
   public void itemStateChanged(ItemEvent e)
   {
   	 if(e.getSource()==red)color=Color.red;
   	 if(e.getSource()==green)color=Color.green;
   	 if(e.getSource()==blue)color=Color.blue;
   	 if(e.getSource()==yellow)color=Color.yellow;
   	 repaint();
   }
   public void paint(Graphics g)
   {
   	 g.setColor(color);
   	 g.fillOval(60,60,40,40);
   }
}