I want a simple popup for few seconds

Popup popup = new Popup(null, new JLabel("Done"), 10, 10);
popup.show();

try {
   Thread.sleep(2000);
} catch (InterruptedException ie) {
}
popup.hide();

Everything is OK except I don't see the word "Done" in the label.
If I comment out the lines for try, Thread.sleep(###) and catch
Then I can see the word "Done in the label, then I can't make the popup
for few seconds.

Anyone knows why the word "Done" won't show up if I use Thread.sleep?
Any idea how do I fix the problem?

I don't need JProgressBar nor JMonitor for  my simple application.
I want similar to the Tooltip popup for few seconds, but without
move the mouse pointer to a particular JComponent.

Thank you in advance!