Hello,
I would like your comment about synchronized and
SwingUtilities.invokeLater in this example with javax.swing.Timer:

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

public class MyTimer{

    private Timer timer;

    public MyTimer(){
        initTimer();
    }

    public void startTimer(){
        timer.start();
    }

    public static void main(String[] args) {
        MyTimer myTimer = new MyTimer();
        myTimer.startTimer();
        JOptionPane.showMessageDialog( null, "Wait...","MyTimer" ,
JOptionPane.WARNING_MESSAGE);
    }

    private void initTimer(){
        timer = new Timer( 5000, new ActionListener()
        {
            public void actionPerformed( ActionEvent e )
            {
                doAction();
            }
        } );
    }

    private void doAction(){
        System.out.println("Hello!");
    }
}

///////////////////////////////////////////////////////////////////////
/*
* Second
*/
    .....

      public static void main(String[] args) {
        MyTimer myTimer = new MyTimer();
        myTimer.startTimer();
        JOptionPane.showMessageDialog( null, "Wait...","MyTimer" ,
JOptionPane.WARNING_MESSAGE);
    }
      ......
    private synchronized void doAction(){
        System.out.println("Hello!");
    }

/////////////////////////////////////////////////////////////
/*
* Third
*/

......

    public static void main(String[] args) {
        MyTimer myTimer = new MyTimer();
        myTimer.startTimer();
        SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                JOptionPane.showMessageDialog( null, "Wait...","MyTimer" ,
JOptionPane.WARNING_MESSAGE);
            }
        });

    }

.......

private void doAction(){
        System.out.println("Hello!");
    }

//////////////////////////////////////////////////////////////
/*
* Fourth
*/

......

    public static void main(String[] args) {
        MyTimer myTimer = new MyTimer();
        myTimer.startTimer();
        SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                JOptionPane.showMessageDialog( null, "Wait...","MyTimer" ,
JOptionPane.WARNING_MESSAGE);
            }
        });

    }

.......

private synchronized void doAction(){
        System.out.println("Hello!");
    }

Thanks,
Paolo