Timer in java using Eclipse

I'm trying to do a little program in Java using Eclipse, and I'm a little bit lost.

Could anybody explain me (in a "for dummies way") what do I have to do for repaint a form using a timer?

I'm trying to do something as simple as a clock. I need a timer to repaint it every second.

Something like this:

private void activateTimer()
{
    ActionListener myAction;
    myAction = new ActionListener () 
    { 
        public void actionPerformed(ActionEvent e) 
        { 
           whatever.redraw();
         } 

    };
    myTimer = new Timer(1000, myAction);
    myTimer.start();
}

When the action must be performed, I receive the error:

*Exception in thread "AWT-EventQueue-0" org.eclipse.swt.SWTException: Invalid thread access*

This is the full exception I receive:

Exception in thread "AWT-EventQueue-0" org.eclipse.swt.SWTException: Invalid thread access
    at org.eclipse.swt.SWT.error(SWT.java:4282)
    at org.eclipse.swt.SWT.error(SWT.java:4197)
    at org.eclipse.swt.SWT.error(SWT.java:4168)
    at org.eclipse.swt.widgets.Widget.error(Widget.java:468)
    at org.eclipse.swt.widgets.Widget.checkWidget(Widget.java:359)
    at org.eclipse.swt.widgets.Control.redraw(Control.java:2327)
    at default.myTimer$1.actionPerformed(myTimer.java:97)
    at javax.swing.Timer.fireActionPerformed(Unknown Source)
    at javax.swing.Timer$DoPostEvent.run(Unknown Source)
    at java.awt.event.InvocationEvent.dispatch(Unknown Source)
    at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
    at java.awt.EventQueue.access$000(Unknown Source)
    at java.awt.EventQueue$3.run(Unknown Source)
    at java.awt.EventQueue$3.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
    at java.awt.EventQueue.dispatchEvent(Unknown Source)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
    at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
    at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
    at java.awt.Eve开发者_开发百科ntDispatchThread.pumpEvents(Unknown Source)
    at java.awt.EventDispatchThread.run(Unknown Source)

Any idea or any sample about refreshing a screen every second?

I've followed the instructions in one of the answers but I'm still receiving the same error.

you have to split that to the separete methods, better would be using javax.swing.Action instead of ActionListener

private void activateTimer(){
    myTimer = new Timer(1000, myAction);
    myTimer.start();
}

private Action myAction = new AbstractAction() {

    private static final long serialVersionUID = 1L;

    @Override
    public void actionPerformed(ActionEvent e) {
          whatever.redraw();
    }
};

Why not use the timer functionality that is built into the SWT Display class?

private void activateTimer(final Display display)
{
    display.timerExec(
        1000,
        new Runnable() {
            public void run() {
                whatever.redraw();
                // If you want it to repeat:
                display.timerExec(1000, this);
            }
        });
}

This page may be useful.

If you use SWT, do it in SWT way :)

EDIT:

The problem is widget should be updated by eclipse's thread. Try this code.

Job job = new Job("My Job") {
@Override
protected IStatus run(IProgressMonitor monitor) {
    Display.getDefault().asyncExec(new Runnable() {
        @Override
        public void run() {
            while(true)
            {
                Thread.sleep(1000);
                whatever.redraw();
            }
        }
    });
    return Status.OK_STATUS;
}
};
job.schedule();