怎样用java 程序写一个时钟程序？最好有代码！谢谢

import java.awt.Color;
import java.util.*;
import java.awt.*;
import java.applet.*;

public class Clock extends Applet implements Runnable
{
Thread timer=null;
Label label;
int lastxs=50,lastys=30,lastxm=50,lastym=30,lastxh=50,lastyh=30;

public void init()
{
label=new Label(" ");
setBackground(Color.white);
add(label);
}
public void paint(Graphics g)
{
int xh,yh,xm,ym,xs,ys,s,m,h,xcenter,ycenter;
Date rightnow=new Date();
String today=rightnow.toLocaleString();
label.setText(today);
s=rightnow.getSeconds();
m=rightnow.getMinutes();
h=rightnow.getHours();
xcenter=100;
ycenter=80;

xs=(int)(Math.cos(s*3.14f/30-3.14f/2)*45+xcenter);
ys=(int)(Math.sin(s*3.14f/30-3.14f/2)*45+ycenter);
xm=(int)(Math.cos(m*3.14f/30-3.14f/2)*45+xcenter);
ym=(int)(Math.sin(m*3.14f/30-3.14f/2)*45+y