import java.awt.*;
import java.util.*;
import javax.swing.*;
public class clock extends JFrame implements Runnable
{   Thread clock;
    public clock()
      { 
      	super("數字時鐘");
      	setFont(new Font("Times New Raman",Font.BOLD,20));
      	start();
      	setSize(120,90);
      	setLocation(300,50);
      	setVisible(true);
      	setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      }
      
    
    public void start()
      {
      	if(clock==null){clock=new Thread(this);
      		            clock.start();
      		            }
      }  
      
     public void run()
     {
     	while(clock!=null)
     	  {  repaint();
     	     try{Thread.sleep(1000);}
     	     catch(InterruptedException ex){ex.printStackTrace();}
     		 }
     	
     } 
     
     public void stop()
     {  clock=null;}
     
     public void paint(Graphics g)
     {  Graphics2D g2=(Graphics2D)g;
        Calendar now=new  GregorianCalendar();
        String timeInfo="";
        int hour=now.get(Calendar.HOUR_OF_DAY);
        int minute=now.get(Calendar.MINUTE);
        int second=now.get(Calendar.SECOND);
        if(hour<=9)
           timeInfo+="0"+hour+":";
        else
           timeInfo+=hour+":";
              
        if(minute<=9)
           timeInfo+="0"+minute+":";
        else
           timeInfo+=minute+":";
           
        if(second<=9)
           timeInfo+="0"+second;
        else
           timeInfo+=second;
           
        g.setColor(Color.blue);
        Dimension dim=getSize();
        g.fillRect(0,0,dim.width,dim.height);
        g.setColor(Color.cyan);
        g.drawString(timeInfo,20,80);         
     }
      
      
      
      public static void main(String[] args){new clock();}  

}