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Message:

UI Update in a Thread !

Posted by L.COPPEAUX on May 22, 2000 at 11:36 AM

> > Hi,
> > I'm developing one application, in which when I start downloading
> > the information, I want to show its status to user to indicate the
> > amount of downloading finished. But I'm facing the problem.
> >
> > Here is what I had done :-
> > Before I start downloading I starts the thread which is Frame
> > and in that I'm displaying JLabel which should update status of
> > downloading.I will update this JLabel in the loop as the one after
> > one productsInformation is downloaded.
> > After thread has been started, I will start downloading proudctsInfo
> > in my main thread. But strange thing is that my spawned thread,
> > doesn't update the status of downloading. In fact, it doesn't get
> > repainted until all downloading is finished. Once it is finished, it
> > displays the Frame that was spawned from the main Application.

> > Can anybody please guide me in ths ?
> > Any code sample will be most appericated .

> > regards,
> > raju

> Have you tried wait() and notify() methods i.e. stopping/allowing the main thread to sleep for a while and repaint the frame in the mean time ?

You can't update the UI inside a thread directly.
All the UI work must be done in the event-dispatching thread.
When, you want to update the UI inside a thread, you need to use :
SwingUtilities.invokeLater(new Runnable(){
public void run(){
// UI update Work
}
});
invokeLater put the runnable in the event queue and therefore the
UI is updated in a thread-safe manner.
Regards