Frustrated by AWT..need some help

Here's a piece of code that I borrowed from another site and made to
show my traffic light.

I added the 6 methods to turn on and off each light, but I have no idea
what to put in each of them. Is there a way to do this without having
to change my program

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

public class ShapesDemo2D extends JApplet {

     final static Color bg = Color.white;
     final static Color fg = Color.black;
     final static Color red = Color.red;
     final static Color white = Color.white;
     final static Color green = Color.green;
     final static Color amber = Color.yellow;

     public void init() {
         //Initialize drawing colors
         setBackground(bg);
     }

     public void paint(Graphics g) {
         Graphics2D g2 = (Graphics2D) g;
         g2.setPaint(fg);
         // draw Rectangle2D.Double
         g2.draw(new Rectangle2D.Double(1, 1, 170,50));
         // draw Ellipse2D.Double
         g2.setPaint(red);
         g2.draw(new Ellipse2D.Double(1, 1, 50,50));

         g2.setPaint(amber);
         g2.draw(new Ellipse2D.Double(60, 1, 50,50));

         g2.setPaint(red);
         g2.draw(new Ellipse2D.Double(120, 1, 50,50));

         // fill Ellipse2D.Double
         g2.setPaint(red);
         g2.fill (new Ellipse2D.Double(1, 1, 50,50));

         g2.setPaint(amber);
         g2.fill (new Ellipse2D.Double(60, 1, 50,50));

         g2.setPaint(green);
         g2.fill (new Ellipse2D.Double(120, 1, 50,50));

     }
     public void turnRedLightOn()
     {

     }
     public void turnAmberLightOn()
     {

     }
     public void turnGreenLightOn()
     {

     }
     public void turnRedLightOff()
     {

     }
     public void turnAmberLightOff()
     {

     }
     public void turnGreenLightOff()
     {

     }

     public static void main(String s[]) {
         JFrame f = new JFrame("Traffic Light Simulator");
         f.addWindowListener(new WindowAdapter() {
             public void windowClosing(WindowEvent e) {System.exit(0);}
         });
         JApplet applet = new ShapesDemo2D();
         f.getContentPane().add("Center", applet);
         applet.init();
         f.pack();
         f.setSize(new Dimension(200,100));
     }

}

My thinking is that should be able to call turnGreenLightOff and
have the green ellispe be repainted "white" to indicate that it's off.
But I'm stuck. Is there a way to call the turnGreenLightOff method from
void in this way or do I have to do something else? And if so, what do I
need to put in the method, I've googled for the solution and have also
looked in several of my books, but I haven't found anything that will
work.....