Moving ball in applet

import java.applet.*;
import java.awt.*;
import java.lang.*;
import java.math.*;
import java.awt.Color;


/*<applet code="ball" height=100 width=100></applet>
  */
public class ball extends Applet implements Runnable

{
int i=0,j=0;

Thread t;
public void init()
{
t=new Thread(this);
t.start();
}
public void run()
{
int sec=0;
setSize(1200,1200);
try
{
while(true)
{
repaint();
sec+=1;

t.sleep(100);

}
}catch(Exception e)
{
System.out.println(e);
}
}

public void update(Graphics g)
{
paint(g);
}
public void paint(Graphics g)
{
setBackground(Color.black);

Dimension d= getSize();
g.setColor(Color.black);
g.fillRect(0,0,d.width,d.height);
g.setColor(Color.white);
g.fillOval(i+10,j+10,100,100);
i=i+10;
g.setColor(Color.black);


}
}