Swing Thread trouble

[Lu Battist]

I have an image viewer program in which I use a label with an Icon to view images. The left and right navigation buttons work, but I what I really want is a startShow and stopShow buttons. The startShow btn should iterate through all the images automatically with a 2 second pause starting with the current one and stopShow button should stop the show at the present image. If I add no pause, it actually works but is too fast. If I add a pause, it doesn't display any images. What am I doing wrong?
Here is some of the relevant code.

//instance variable
private final Thread showThread = new Thread() {
  public void run() {
showImages(this);
  }
};
//Button Listeners
leftBtn.addActionListener(new ActionListener() {
  public void actionPerformed(ActionEvent ae) {
    try {
      imageList.prev();
    } catch (llb.home.util.FileNotFoundException e) {
      System.err.println(e);
    }
    Thread t = new Thread() {
      public void run() {
        showImage();
        SwingUtilities.invokeLater(new Runnable() {
          public void run() {
            label.doLayout();
  }
        });
      }
    };
    t.start();
    if (!imageList.hasPrev()) {
      leftBtn.setEnabled(false);
    }
    if (!rightBtn.isEnabled()) {
      rightBtn.setEnabled(true);
      startBtn.setEnabled(true);
    }
  }
} );
rightBtn.addActionListener(new ActionListener() {
  public void actionPerformed(ActionEvent ae) {
    try {
      imageList.next();
    } catch (llb.home.util.FileNotFoundException e) {
      System.err.println(e);
    }
    Thread t = new Thread() {
      public void run() {
        showImage();
        SwingUtilities.invokeLater(new Runnable() {
          public void run() {
            label.doLayout();
          }
        });
      }
    };
    t.start();
    if (!imageList.hasNext()) {
      rightBtn.setEnabled(false);
      startBtn.setEnabled(false);
    }
    if (!leftBtn.isEnabled()) {
      leftBtn.setEnabled(true);
    }
  }
} );
startBtn.addActionListener(new ActionListener() {
  public void actionPerformed(ActionEvent ae) {
    startBtn.setEnabled(false);
    leftBtn.setEnabled(false);
    rightBtn.setEnabled(false);
    stopBtn.setEnabled(true);
    showThread.start();
  }
} );
stopBtn.addActionListener(new ActionListener() {
  public void actionPerformed(ActionEvent ae) {
  stopBtn.setEnabled(false);
  showThread.interrupt();
  }
} );
...
private void showImages(Thread t) {
  File f = null;
  Icon image = null;
  try {
    while (imageList.hasNext()) {
      imageList.next();
      f = imageList.getFile();
      image = new ImageIcon(f.getAbsolutePath());
      label.setText(f.getName());
      label.setIcon(image);
      label.setHorizontalTextPosition(SwingConstants.CENTER);
      label.setVerticalTextPosition(SwingConstants.TOP);
      SwingUtilities.invokeLater(new Runnable() {
        public void run() {
          label.doLayout();
        }
      });
      if (t.isInterrupted()) {
        throw new InterruptedException();
      } else {
        t.wait(2000);
      }
    }
  } catch (llb.home.util.FileNotFoundException e) {
    System.err.println("showImages() - " + e);
  } catch (InterruptedException ie) {
    ;
  } finally {
    stopBtn.setEnabled(false);
    if (imageList.hasPrev()) {
      leftBtn.setEnabled(true);
    }
    if (imageList.hasNext()) {
      rightBtn.setEnabled(true);
      startBtn.setEnabled(true);
    }
  }
}
private void showImage() {
  File f = null;
  try {
    f = imageList.getFile();
  } catch (llb.home.util.FileNotFoundException e) {
    System.err.println("showImage() - " + e);
    return;
  }
  Icon image = new ImageIcon(f.getAbsolutePath());
  label.setText(f.getName());
  label.setIcon(image);
  label.setHorizontalTextPosition(SwingConstants.CENTER);
  label.setVerticalTextPosition(SwingConstants.TOP);
}

[Kathy Walrath]

It looks like you're waiting in the event thread, which stops all event-processing and painting in the app. What you should use instead is a Swing Timer. You can find information about Swing Timers here:
http://java.sun.com/docs/books/tutorial/uiswing/misc/timer.html
In fact, there's some code in there which is very close to what you need -- it performs an action once a second for as long as there's anything to do.
[ April 29, 2004: Message edited by: Kathy Walrath ]