I have a JDialog with a thread in it. It sporadically gives me a ClassCastException when the dialog is created (which means I can have succesful ones with no exception), and I have no clue to where it should occur. 

Here's a snippet of my JDialog class

```
public class ConfirmExitDialog extends JDialog implements Runnable,
    ActionListener {
private static final long serialVersionUID = -8762051370686039110L;
private Thread dialogThread;
private boolean running;
private int result, count = 60;
private HandleExit  handleExit = null;

// GUI
private JOptionPane optionPane;
private JLabel msgLabel = new JLabel();
private JButton btnYes;
private JButton btnNo;

private void updateLabelText() {
    msgLabel.setText("<html>Ønsker du at afslutte dagens salg?<br>Programmet afslutter automatisk om " + count + " sekunder.</html>");
}

public int getResult() {
    return result;
}

public ConfirmExitDialog(Frame frame, HandleExit handleExit) {
    super(frame, false);
    this.handleExit = handleExit;

    setTitle("Afslut dagens salg?");
    display();

    running = true;
    if (dialogThread == null) {
        dialogThread = new Thread(this, "ConfirmExitDialog");
        dialogThread.start();
    }
    this.setModal(true);
}

public void close() {
    if (dialogThread != null)
        running = false;
}

private void display() {
    setLayout(new BorderLayout());

    // Buttons
    btnYes = new JButton("Ja");
    btnYes.addActionListener(this);
    btnYes.setMnemonic('J');
    add(btnYes, BorderLayout.WEST);
    btnNo = new JButton("Nej");
    btnNo.addActionListener(this);
    btnNo.setMnemonic('N');
    add(btnNo, BorderLayout.EAST);
    JButton[] buttons = { btnYes, btnNo };

    updateLabelText();
    optionPane = new JOptionPane(msgLabel, JOptionPane.QUESTION_MESSAGE,
            JOptionPane.YES_NO_OPTION, null, buttons, buttons[0]);
    setContentPane(optionPane);

    setDefaultCloseOperation(DISPOSE_ON_CLOSE);

    // Handle window closing correctly.
    setDefaultCloseOperation(DO_NOTHING_ON_CLOSE);
    addWindowListener(new WindowAdapter() {
      public void windowClosing(WindowEvent we) {
        /*
         * Instead of directly closing the window, we're going to change the
         * JOptionPane's value property.
         */
        optionPane.setValue(new Integer(JOptionPane.CLOSED_OPTION));
      }
    });

    pack();
    setVisible(true);   
}

private void countDown() {
    updateLabelText();
    count--;
}

@Override
public void run() {
    // TODO Auto-generated method stub

    try {
        display();
        while (running && count > 0) {
            System.out.println("Countdown " + count);
            pack();
            countDown();
            Thread.sleep(1000);
        }

        setVisible(false);
        if (count == 0)
            handleExit.closeApplication(true, true);

    } catch (InterruptedException ie) {
        // Thread stopped
    }
}

@Override
public void actionPerformed(ActionEvent event) {
    Object src = event.getSource();

    if (src == btnYes) {
        setVisible(false);
        result = JOptionPane.YES_OPTION;
        running = false;
        handleExit.closeApplication(true, false);
    }
    if (src == btnNo) {
        setVisible(false);
        result = JOptionPane.NO_OPTION;
        running = false;

    }
}

```

}

Here's the exception cast:

> 
> Exception in thread "AWT-EventQueue-0"
>  java.lang.ClassCastException at
>  javax.swing.LayoutComparator.compare(LayoutComparator.java:61)
>  at
>  java.util.Arrays.mergeSort(Arrays.java:1293)
>  at
>  java.util.Arrays.mergeSort(Arrays.java:1282)
>  at
>  java.util.Arrays.sort(Arrays.java:1210)
>  at
>  java.util.Collections.sort(Collections.java:159)
>  at
>  javax.swing.SortingFocusTraversalPolicy.enumerateAndSortCycle(SortingFocusTraversalPolicy.java:119)
>  at
>  javax.swing.SortingFocusTraversalPolicy.getFirstComponent(SortingFocusTraversalPolicy.java:434)
>  at
>  javax.swing.LayoutFocusTraversalPolicy.getFirstComponent(LayoutFocusTraversalPolicy.java:148)
>  at
>  javax.swing.SortingFocusTraversalPolicy.getDefaultComponent(SortingFocusTraversalPolicy.java:511)
>  at
>  java.awt.FocusTraversalPolicy.getInitialComponent(FocusTraversalPolicy.java:152)
>  at
>  java.awt.Window.getMostRecentFocusOwner(Window.java:2131)
>  at
>  java.awt.DefaultKeyboardFocusManager.dispatchEvent(DefaultKeyboardFocusManager.java:629)
>  at
>  java.awt.Component.dispatchEventImpl(Component.java:4502)
>  at
>  java.awt.Container.dispatchEventImpl(Container.java:2099)
>  at
>  java.awt.Window.dispatchEventImpl(Window.java:2478)
>  at
>  java.awt.Component.dispatchEvent(Component.java:4460)
>  at
>  java.awt.EventQueue.dispatchEvent(EventQueue.java:599)
>  at
>  java.awt.SequencedEvent.dispatch(SequencedEvent.java:101)
>  at
>  java.awt.EventQueue.dispatchEvent(EventQueue.java:597)
>  at
>  java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:269)
>  at
>  java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:184)
>  at
>  java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:174)
>  at
>  java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169)
>  at
>  java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:161)
>  at
>  java.awt.EventDispatchThread.run(EventDispatchThread.java:122)
> 
> 
> 

Thank you.
Daniel