import java.awt.*;
import java.awt.event.*;

class BallThread {

	public static void main(String[] args){
		ThreadFrame f = new ThreadFrame(); //(1)
		f.setSize(400, 400); //(2)
		f.addWindowListener(new WindowAdapter(){ //(3)
			public void windowClosing(WindowEvent e){
				System.exit(0);}});
		f.show();
	}

}


class ThreadFrame extends Frame implements Runnable {

	Thread th;
	int x;

	ThreadFrame() {
		x = 10;
		th = new Thread(this);
		th.start();
	}

	public void run() {
		while (true) {
			repaint();   
			x = x + 10;

			try {
				th.sleep(100);    
			}
			catch (InterruptedException e) {}
		}
	}

	public void paint(Graphics g) {
		g.fillOval(x, 50, 10, 10);
	}

}