Updating frame content between Thread.sleep() calls

Question

I have several JLabels in a Frame. What I want is to update the content of the labels (to be more precise, the ImageIcons), but with pauses in between each update (lets say 1 second). So, I want to change the content of one label, have those changes show on screen, then, wait for a second and change the content of the second label, show the changes, wait for a second, change the next label, and so on...
What I'm doing is:
change label 1
Thread.sleep(1000);
change label 2
Thread.sleep(1000);
change label 3
Thread.sleep(1000);
...And the problem is that the individual changes are not shown on screen until the whole process has finished. It does pause after each change, but the change to the particular label is not shown afterwards. Then, when the whole process is finished, the changes to all the labels are shown simultaneously on screen.
I have tried calling repaint() and validate() after each call to Thread.sleep(), but it makes no difference.
Why are the changes not updated on screen until the end?
How can I achieve what I'm trying to do?
Many thanks in advance.

Answer 1

You're sleeping in the main thread, so you're holding up the paint thread too...
I'd trying extending each label / visual component, to include it's own timer and thread.
eg. ( not compiled nor tested, but addresses all the main points... )
regards,
Owen
public class myLabel extends JLabel implements runnable
    boolean animate = true;
    Thread paintThread;
     public myLabel ( )
          super();
          paintThread = new Thread ( this );
     public void startAnimation ( )
          if ( animate == false )
             animate = true;
             paintThread.start();
     pubic void stopAnimation ( )
         animate = false;
     public void run ( )
           while ( !animate )
               Thread.sleep ( 1000 );
                final Runnable runnable = new Runnable()
                    public void run()
                          // change label text
                          // Make any Swing / GUI changes here                      
                    } // run
               };    // runnable
               // force/flag this label as requiring a repaint
               invalidate();              
               // NB : You must use this to avoid multi-threaded problems with Swing
               SwingUtilities.invokeLater(runnable);
}