import java.awt.*;

public class TrafficCanvas extends Canvas {

  public Dimension getMinimumSize() {
    return new Dimension(100,260);
  }
  public Dimension getPreferredSize() {
    return getMinimumSize();
  }

  public void paint (Graphics g) {
    g.setColor (Color.black);
    g.fillRect (10, 10, 80, 240);
    g.setColor (Color.red);
    g.fillOval (20, 20, 60, 60);
    g.setColor (Color.yellow);
    g.fillOval (20, 100, 60, 60);
    g.setColor (Color.green);
    g.fillOval (20, 180, 60, 60);
  }

  public static void main (String[] args) {
    Frame f = new Frame("Traffic Light Test");
    TrafficCanvas theLight = new TrafficCanvas();
    f.setLayout ( new FlowLayout() );
    f.add(theLight);
    f.setSize(200,300); // or: pack();
    f.setVisible(true);
    // no event handling, use Ctrl-C to stop this program.
  }
}