import java.awt.event.*;
import java.awt.*;import java.util.Date;
class Example19_9 extends Frame implements Runnable,ActionListener
{  Thread thread=null; TextArea text=null;
   Button b_start=new Button("Start"),b_stop=new Button("Stop");
   Example19_9()
   {  thread=new Thread(this);
      text=new TextArea();add(text,"Center");
      Panel p=new Panel();p.add(b_start);p.add(b_stop); 
      b_start.addActionListener(this);
      b_stop.addActionListener(this) ;
     add(p,"North");setVisible(true);
     setSize(500,500);pack();setSize(500,500);
     setResizable(false);                     //讓窗口的大小不能被調整。
     addWindowListener(new WindowAdapter()
                   {  public void windowClosing(WindowEvent e)
                     {System.exit(0);
                     }
                   });
   }
   public void actionPerformed(ActionEvent e)
   {  if(e.getSource()==b_start)
        {
           if(!(thread.isAlive()))
              {  thread=new Thread(this);
              }    
          try {  thread.start();
              }
          catch(Exception e1)
              {  text.setText("線程沒有結束run方法之前，不要再調用start方法");
              }  
       }
      else if(e.getSource()==b_stop)
       {  thread.interrupt();
       }
   }
   public void run()
   {  while(true)
           {  text.append("\n"+new Date());
               try{  thread.sleep(1000);
                  }
               catch(InterruptedException ee)
                  {  text.setText("我被消滅");return;//結束run語句,消滅該線程。
                  }
            } 
   }
   public static void main(String args[])
   {  Example19_9 tt=new Example19_9();
   }
}