Simulates a Traffic Light

import java.awt.*;
import java.applet.*;
import java.awt.event.*;
/*
<applet code="traffic.class" width=500 height=500>
</applet>
*/
public class traffic extends Applet implements ActionListener
{
 int i=0; 
 Button R,O,G;
 public void init()
 {
  setBackground(Color.white);
  setForeground(Color.black);
  R=new Button("red");
  O=new Button("orange");
  G=new Button("green");
  add(R);
  add(O);
  add(G);
  R.addActionListener(this);
  O.addActionListener(this);
  G.addActionListener(this);
 }
 public void actionPerformed(ActionEvent ae)
 {
  String s=ae.getActionCommand();
  if(s.equals("red"))
   i=1;
  if(s.equals("orange"))
   i=2;
  if(s.equals("green"))
   i=3;
  repaint();
 }
 public void paint(Graphics g)
 {
  g.setColor(Color.yellow);
  g.drawRect(50,50,100,200);
  g.fillRect(50,50,100,200);
  g.setColor(Color.black);
  g.drawOval(80,70,30,30);
  g.drawOval(80,130,30,30);
  g.drawOval(80,190,30,30);
  g.setColor(Color.yellow);
  g.drawLine(100,250,100,900);

  if(i==1)
  {
   g.setColor(Color.red);
   g.fillOval(80,70,30,30);
  }
  if(i==2)
  {
   
   g.setColor(Color.orange);
   g.fillOval(80,130,30,30);
  }
  if(i==3)
  {
   g.setColor(Color.green);
   g.fillOval(80,190,30,30);
  }
 }
}