數位時鐘

 import java.awt.FlowLayout;  
 import java.awt.event.ActionEvent;  
 import java.awt.event.ActionListener;  
 import java.text.SimpleDateFormat;  
 import java.util.Date;  
 import javax.swing.JFrame;  
 import javax.swing.JLabel;  
 import javax.swing.JPanel;  
 import javax.swing.Timer;  
 public class DigitalClock extends JLabel {  
      private String pattern;  
      private Timer timer;  
      private int delay;  
      public DigitalClock(String pattern) {  
           this.pattern = pattern;  
           this.delay = 1000;  
           createTimer();  
           timer.start();  
      }  
      public DigitalClock(String pattern, int delay) {  
           this.pattern = pattern;  
           this.delay = delay;  
           createTimer();  
           timer.start();  
      }  
      public DigitalClock() {  
           pattern = "hh:mm:ss a";  
           this.delay = 1000;  
           createTimer();  
           timer.start();  
      }  
      private void createTimer() {  
           timer = new Timer(delay, new ActionListener() {  
                public void actionPerformed(ActionEvent arg0) {  
                     setText(new SimpleDateFormat(pattern).format(new Date()));  
                }  
           });  
      }  
      public static void main(String[] args) {  
           JFrame frame = new JFrame();  
           frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);  
           frame.setBounds(100, 100, 229, 102);  
           JPanel contentPane = new JPanel();  
           frame.setContentPane(contentPane);  
           contentPane.setLayout(new FlowLayout(FlowLayout.CENTER, 10, 10));  
           DigitalClock digitalClock = new DigitalClock();  
           contentPane.add(digitalClock);  
           frame.setVisible(true);  
      }  
 }  

參考來源 : http://tw.knowledge.yahoo.com/question/question?qid=1013061801638 , strawman