ProgressMonitor not showing properly

Question

Sorry for cross-posting, but in general Java programming, nobody seems to have any idea. The original thread is http://forum.java.sun.com/thread.jsp?forum=31&thread=319651
Here's what it's about:
I've got a little prob using ProgressMonitor. I'm coding an Applet which loads some images. Since this task may take a while, I'm trying to use ProgressMonitor to show a dialog window with the corresponding progressbar to indicate how much work's done already.
My code looks like this:
// Image[] images has been filled before.
// mt is a MediaTracker which surveys the loading.
ProgressMonitor pm = new ProgressMonitor(
  null,
  "Loading images",
  0,
  images.length - 1
for (int i = 0; i < images.length; i++) {
  pm.setProgress(i);
  pm.setNote(images[ i ].toString());
  // actual image loaded?
  while (!mt.checkID(i, true)) { 
    // if not wait:
    Thread.sleep(10); 
if (mt.checkAll() && !pm.isCanceled() && !mt.isErrorAny()) {
  pm.close();
// everything successfully loadedThe loading of the images works fine. My only prob is with the ProgressMonitor which starts showing after the default time (might be one second) - but the frame it shows is corrupt. You can see the outlines of it, but none of the contents is displayed - not to talk of the progressbar. Simply nothing.
Did anyone encounter this prob as well and has some ideas what's wrong? Any help would be appreciated.
Cheers,
kelysar

Answer 1

Hi again.
I get the point described in that other thread - but I've got a little problem transferring the solution to my problem. The situation is this:
I've got as class derived from JFrame which shall show thumbnails of some images. In the constructor of that class I call an init()-method in which I'm loading the images to be displayed. I want the ProgressMonitor to survey the loading of the images since that's what is taking most time. In short and pseudo-coded this looks like:
class PicFrame extend JFrame {
  public PicFrame() {
    // do all initializations, and..
    init();  // this shall load the images etc.
    pack();
    show();
  public void init() {
    ProgressMonitor pm = new ProgressMonitor(...);
    pm.setNote("starting");
    pm.setProgress(1);
    for (all images specified in an array) {
      pm.setProgress(index of current image);
      pm.setNote(name of image);
      load image with a MediaTracker
    if (not cancelled and all images loaded fine) pm.close();
}How am I able to separate the loading of the images into a second thread and update the ProgressMonitor without being blocked by the loading thread?
I'm still chewing on this - so I'd be glad to see any suggestions.
Thanks again for the idea.
cheers,
kelysar