Controlling a thread from the gui

Question

Hi ive written a small piece of code that demonstrates the problem im having:
package Util;
import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
public class Monitor implements ActionListener {
     Mon mon = new Mon();
     public Monitor() {
          JFrame frame = new JFrame();
          JButton start = new JButton("Start");
          JButton pause = new JButton("Pause");
          pause.addActionListener(this);
          start.addActionListener(this);
          frame.setLayout(new FlowLayout());
          frame.add(start);
          frame.add(pause);
          frame.setVisible(true);
          frame.pack();
     public void actionPerformed(ActionEvent e) {
          if (e.getActionCommand() == "Start") {
               mon.start();
          } else {
               mon.pause();
     public static void main(String args[]) {
          new Monitor();
class Mon extends Thread {
     public void run() {
          while (true) {
               System.out.println("Running...");
               try {
                    sleep(1000);
               } catch (InterruptedException e) {
                    e.printStackTrace();
     public synchronized void pause() {
          try {
               wait();
          } catch (InterruptedException e) {
               // TODO Auto-generated catch block
               e.printStackTrace();
}I was wondering whether anyone could help me fix this or point out where im going wrong. Whenever the pause button is pressed, i want the thread to temporarily stop printing out "Running" until start is pressed again. At the mo, when i press the pause button, the gui locks up and the thread continues to print out running.
Cheers.

Answer 1

Thanks da.futt your advice helped me solve the problem, working example:
package Util;
import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
public class Monitor implements ActionListener {
     Mon mon = new Mon();
     public Monitor() {
          JFrame frame = new JFrame();
          JButton start = new JButton("Start");
          JButton pause = new JButton("Pause");
          pause.addActionListener(this);
          start.addActionListener(this);
          frame.setLayout(new FlowLayout());
          frame.add(start);
          frame.add(pause);
          frame.setVisible(true);
          frame.pack();
     public void actionPerformed(ActionEvent e) {
          if (e.getActionCommand() == "Start") {
               try {
                    mon.start();
               } catch (Exception ex) {
                    mon.restart();
          } else {
               mon.pause();
     public static void main(String args[]) {
          new Monitor();
class Mon extends Thread {
     private boolean running = true;
     public void run() {
          while (true) {
               if (running) {
                    System.out.println("Running...");
                    try {
                         sleep(1000);
                    } catch (InterruptedException e) {
                         e.printStackTrace();
               } else {
                    synchronized (this) {
                         try {
                              wait();
                         } catch (InterruptedException e) {
                              // TODO Auto-generated catch block
                              e.printStackTrace();
     public void restart() {
          running = true;
          synchronized (this) {
               notify();
     public void pause() {
          running = false;
          synchronized (this) {
}