import javax.swing.JApplet;
import javax.swing.Timer;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import java.awt.Graphics;
import java.awt.Color;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;

/**
 * Write a description of class TimerTest here.
 *
 * @author (your name)
 * @version (a version number or a date)
 */
public class TimerTest extends JApplet implements ActionListener
{
    private Timer timer;
    private final int DELAY = 20;
    int x, y;
    int xchange = 7;
    int ychange = 7;

    public void init()
    {
        timer = new Timer(DELAY, this);
        addMouseListener(new MouseHandler());
    }

    public void actionPerformed(ActionEvent e)
    {
        x += xchange;
        y += ychange;
        if(x < 0 || x > 480)
            xchange *= -1;
        if(y < 0 || y > 320)
            ychange *= -1;
        repaint();
    }

    private class MouseHandler extends MouseAdapter
    {
        public void mouseClicked(MouseEvent e)
        {
            if(timer.isRunning())
            {
                timer.stop();
            }
            else
            {
                timer.start();
            }
        }
    }

    public void paint(Graphics g)
    {
        g.fillRect(0, 0, 500, 500);
        g.setColor(Color.RED);
        g.fillOval(x, y, 10, 10);
    }
}