RectangleMover.java

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JFrame;
import javax.swing.Timer;

public class RectangleMover
{
   public static void main(String[] args)
   {
      JFrame frame = new JFrame();

      frame.setSize(FRAME_WIDTH, FRAME_HEIGHT);
      frame.setTitle("An animated rectangle");
      frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

      final RectangleComponent component = new RectangleComponent();
      frame.add(component);

      frame.setVisible(true);
      
      class TimerListener implements ActionListener
      {
         public void actionPerformed(ActionEvent event)
         {
            component.moveBy(1, 1);
         }
      }

      ActionListener listener = new TimerListener();

      final int DELAY = 100; // Milliseconds between timer ticks
      Timer t = new Timer(DELAY, listener);
      t.start();      
   }
   
   private static final int FRAME_WIDTH = 300;
   private static final int FRAME_HEIGHT = 400;
}