import java.applet.Applet; 
import java.util.Date; 
import java.util.*; 
import javax.swing.*; 
import java.awt.Graphics; 
import java.util.Calendar; 
import java.util.GregorianCalendar; 


//通過Runnable接口定義線程類 
public class RunnableThread extends JApplet implements Runnable 
{ 
Thread clockThread; 
public void start() 
{ 
if (clockThread==null) 
{ 
clockThread=new Thread(this,"Clock"); 
clockThread.start(); 
} 
} 

public void run() 
{ 
while(clockThread!=null) 
{ 
repaint();//實際上是顯示一個時鐘 
try 
{ 
clockThread.sleep(1000); 
}catch(InterruptedException e) {} 
} 
} 


public void paint(Graphics g) 
{ 
super.paint(g); 
Calendar now = GregorianCalendar.getInstance(); 
g.drawString(now.get(Calendar.HOUR)+":"+now.get(Calendar.MINUTE)+":"+now.get(Calendar.SECOND),5,10); 

} 

public void stop() 
{ 
clockThread = null; 
clockThread=null; 
} 


}