import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class ThreaderWebStart extends JFrame {

   private JTextArea ta = new JTextArea();
   private JButton b1 = new JButton("Start T1");
   private JButton b2 = new JButton("Start T2");
   private T1 t1;
   private T2 t2 = new T2(ta);

   public static void main(String[] args) {
      new ThreaderWebStart();
   }
   
   public ThreaderWebStart() {
      JScrollPane scrollPane = new JScrollPane(ta);
      scrollPane.setHorizontalScrollBarPolicy(ScrollPaneConstants.HORIZONTAL_SCROLLBAR_NEVER); 

      b1.addActionListener(new L());
      b2.addActionListener(new L());

      JPanel p = new JPanel();
      p.setLayout(new FlowLayout());
      p.add(b1);
      p.add(b2);
      getContentPane().add("Center", scrollPane);
      getContentPane().add("South", p);

      setSize(300, 200);
      show();
   }

   class L implements ActionListener {
      public void actionPerformed(ActionEvent ae) {
         if(ae.getSource() == b1) {
            if(b1.getText().equals("Start T1")) {
               t1 = new T1(ta);
               t1.startT();
               b1.setText("Stop T1");
            } else {
               t1.stopT();
               t1 = null;
               b1.setText("Start T1");
            }
         } else {
            if(b2.getText().equals("Start T2")) {
               t2.startT();
               b2.setText("Stop T2");
            } else {
               t2.stopT();
               b2.setText("Start T2");
            }
         }
      }
   }
}

class T1 extends Thread {

   private JTextArea ta;
   private boolean loopIt = false;

   public T1(JTextArea ta) {
      this.ta = ta;
   }

   public void startT() {
      loopIt = true;
      start();
   }

   public void stopT() {
      loopIt = false;
   }

   public void run() {
      while(loopIt) {
         ta.append("T1 running\n");
         ta.setCaretPosition(ta.getText().length()); 
         try {
            sleep(1000);
         } catch(InterruptedException ie) {}
      }
   }
}

class T2 implements Runnable {

   private JTextArea ta;
   private Thread t;

   public T2(JTextArea ta) {
      this.ta = ta;
   }

   public void startT() {
      t = new Thread(this);
      t.start();
   }

   public void stopT() {
      t = null;
   }

   public void run() {
      while(t == Thread.currentThread()) {
         ta.append("T2 running\n");
         ta.setCaretPosition(ta.getText().length()); 
         try {
            t.sleep(1000);
         } catch(InterruptedException ie) {}
      }
   }
}