Threads: Timer

import java.awt.*;
import java.awt.event.*;   // for ActionListener

class Timer extends Thread
{
   TextField out;
   int i=0;
   
   Timer (TextField out) { this.out = out;   }
   
   public void run()
   {
      while (true)
      {
         try
         {
            sleep(1000);
         }
         catch (Exception e) {  }
         out.setText(String.valueOf(i++));
      }
   }
}

public class SecTimer extends java.applet.Applet
                      implements ActionListener
{
   TextField out;
   Button begn, done, susp, cont;
   Timer timer;
   
   public void init()
   {
      setLayout(new BorderLayout());
      add("Center", out = new TextField());
      out.setEditable(false);
      out.setBackground(new Color(200,200,255));
      out.setFont(new Font("TimesRoman",Font.BOLD,48));
      
      Panel p = new Panel();
      p.setLayout(new GridLayout(1,4));
      p.add(begn = new Button("Start"));
      p.add(done = new Button("Stop"));
      p.add(susp = new Button("Suspend"));
      p.add(cont = new Button("Resume"));
      add("South", p);
            
      begn.addActionListener(this);
      done.addActionListener(this);
      susp.addActionListener(this);
      cont.addActionListener(this);
   }
            
   public void actionPerformed (ActionEvent event)
   {
      if (event.getSource() == begn)
      {
         timer = new Timer(out);
         timer.start();
      }
      else
      if (event.getSource() == done)
      {
         timer.stop();
         timer = null;
      }
      else
      if (event.getSource() == susp)
      {
         if (timer != null) timer.suspend();
      }
      else
      if (event.getSource() == cont)
      {
         if (timer != null) timer.resume();
      }
   }
}