Java program to implement thread, applets and graphics by implementing animation of ball moving.

import java.awt.*;

import java.applet.*; /* */

public class MovingBall extends Applet implements Runnable

{

int x, y, dx, dy, w, h;

Thread t;

boolean flag;

public void init ()

{

w = getWidth ();

h = getHeight ();

setBackground (Color.yellow);

x = 100;

y = 10;

dx = 10;

dy = 10;

} public void start ()

{

flag = true;

t = new Thread (this);

t.start ();

} public void paint (Graphics g)

{

g.setColor (Color.blue);

g.fillOval (x, y, 50, 50);

} public void run ()

{

while (flag)

{

if ((x dx <= 0) || (x dx >= w))

dx = -dx;

if ((y dy <= 0) || (y dy >= h))

dy = -dy;

x += dx;

y += dy;

repaint ();

try

{

Thread.sleep (300);

}

catch (InterruptedException e)

{

}

}

}

public void stop ()

{

t = null;

flag = false;

}}