Question

I’m using the following method to display a frame:

public static void createImage(final String url, final String file, final String filetype) {
        UIUtils.setPreferredLookAndFeel();
        NativeInterface.open();
        SwingUtilities.invokeLater(new Runnable() {

            @SuppressWarnings("deprecation")
            @Override
            public void run() {

                frame = new JFrame();
                WebsiteThumbnailCreator ex = new WebsiteThumbnailCreator(url, file, filetype);

                frame.getContentPane().add(ex, BorderLayout.CENTER);
                frame.setSize(FRAMESIZE);
                frame.setLocationByPlatform(true);
                frame.setVisible(true);
                frame.hide();
            }

        });

        NativeInterface.runEventPump(); 
  }

Then i do some calculation and after that, I want to dispose the frame again:

try {
   ImageIO.write(rendered, filetype, new File(file + "." + filetype));
   frame.dispose();
   logger.trace("Tried to dispose the frame");
} catch (IOException e) {
   logger.fatal(e.getMessage());
} finally {
    logger.debug("Try to dispose the frame");
    frame.dispose();
}

I can see the log messages but however, the VM is still running. I want to also terminate it. What am I doing wrong?

There seems to still be running one non deamon thread, but I can’t see why:

Answer 1

You’re not setting the JFrame’s default close operation and it’s defaulting to JFrame.HIDE_ON_CLOSE.

Add to your JFrame set up code:

frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

If your JFrame is your application and you want to exit everything when the JFrame closes, or

frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);

if your JFrame is not the whole application and you want to stop the Swing thread but continue processing.

For more on this, please check out the JFrame API

Edit:
Regarding your comment,

@HovercraftFullOfEels okay if what you say is right why is my frame disappearing in this code: public static void frameTest() throws InterruptedException { final JFrame jf = new JFrame(“Hello World”); jf.setBounds(100, 100, 400, 400); jf.setVisible(true); Thread.sleep(8000); SwingUtilities.invokeLater(new Runnable() { public void run() { // TODO Auto-generated method stub jf.dispose(); } }); }

Which I translate to:

public static void frameTest() throws InterruptedException {
  final JFrame jf = new JFrame("Hello World");
  jf.setBounds(100, 100, 400, 400);
  jf.setVisible(true);
  Thread.sleep(8000);
  SwingUtilities.invokeLater(new Runnable() {
     public void run() {
        jf.dispose();
     }
  });
}

This only exits if there are no more non-daemon threads left. If you give it a non-daemon thread, this will keep running. For e.g.,

public static void main(String[] args) {
  new Thread(new Runnable() {
     public void run() {
        for (int i = 0; i < 30; i++) {
           System.out.println("i := " + i);
           try {
              Thread.sleep(1000);
           } catch (InterruptedException e) {
              e.printStackTrace();
           }
        }
     }
  }).start();
  try {
     frameTest();
  } catch (InterruptedException e) {
     e.printStackTrace();
  }
}

Your code will keep running in this example.