Suggestions for debugging the event queue

Question

Hello,
I have an issue where an exception is thrown inside the AWT-EventQueue-0 and I can't quite figure out where it's coming from. I can replicate it relatively easily, but the action that I do to replicate it actually does all kinds of stuff behind the scenes so it's not so easy to sort out what's going on. I'm debugging with eclipse if it matters. The stack trace mentions none of my code and only mentions java library code. I tried overriding dispatchEventImpl in the components I wrote that are involved in the aforementioned action that causes it to happen, with hope of catching the exception in there and putting a breakpoint or something to give me a clue, but apparently dispatchEventImpl cannot be overridden (not sure why). Ofcourse, once the EventQueue dies from this exception so does the rest of the GUI so that's no help either. I tried adding a break on uncaught ClassCastExceptions and make the break suspend the whole VM instead of just the one thread, and then I look at the two processor threads involved with the action above and that wasn't too much help, they were sitting waiting to read something from the queue, meaning it whatever is happening in the EventQueue is delayed enough that I can't rely on catching it that way. Any and all suggestions/hints/etc are highly appreciated.
The components in question have a panel that's a Box (vertical) that contains subpanels, each with a title and a table (and those subpanels can be expanded/contracted to show/not show the table), the tables are sorted by one of their columns, the panels are sorted by the title, and panels/table rows are added and/or removed by messages coming in from a remote server. The user can click a button to "accept" a table row (which may appear in several of the subpanel tables) at which point the server is alerted to this, and any place this row is shown is removed).
Here is the stack trace (i hope there are no typos, I had to retype it since machine code is on can't be networked to internet):
Exception in thread "AWT-EventQueue-0" java.lang.ClassCastException
at javax.swing.LayoutComparator.compare(Unknown Source)
at java.util.Arrays.mergeSort(Unknown Source)
at java.util.Arrays.mergeSort(Unknown Source)
at java.util.Arrays.mergeSort(Unknown Source)
at java.util.Arrays.mergeSort(Unknown Source)
at java.util.Arrays.mergeSort(Unknown Source)
at java.util.Arrays.mergeSort(Unknown Source)
at java.util.Arrays.mergeSort(Unknown Source)
at java.util.Arrays.mergeSort(Unknown Source)
at java.util.Arrays.sort(Unknown Source)
at java.util.Collections.sort(Unknown Source)
at javax.swing.SortingFocusTraversalPolicy.enumerateAndSortCycle(Unknown Source)
at javax.swing.SortingFocusTraversalPolicy.getFirstComponent(Unknown Source)
at javax.swing.LayoutFocusTraversalPolicy.getFirstComponent(Unknown Source)
at javax.swing.SortingFocusTraversalPolicy.getDefaultComponent(Unknown Source)
at java.awt.FocusTraversalPolicy.getInitialComponent(Unknown Source)
at java.awt.Window.getMostRecentFocusOwner(Unknown Source)
at java.awt.DefaultKeyboardFocusManager.dispatchEvent(Unknown Source)
at java.awt.Component.dispatchEventImpl(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Window.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.SequencedEvent.dispatch(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)

Answer 1

I believe I maaaay have figured out what's going on, though I'm not sure how to go about fixing it, heh.
Ok, so the Box that contains all the subpanels, I'm trying to keep sorted by title of the subpanels. For this reason (and other cross-referencing reasons) I keep a Vector of the object from which the title is constructed in the panel containing the box, as well as a Vector of the subpanels. When I wish to add a new panel I first add it to the Vector (and the title object to its Vector), then I sort those Vectors, then I do a removeAll() on the Box, then re-add the subpanels to the Box while stepping through the subpanel Vector, that way I'm guaranteed they are in order (actually it's probably unnecessary to keep the title vector in addition to the other one, I just haven't gotten around to trimming that kind of stuff out since I've been dealing with this issue). And it works fine.. seemingly.
constructor()
  anEntry = new Vector<MySubpanel>();
  myTitlesVector = new Vector<TitleObject>();
  boxPanel = new Box(BoxLayout.Y_AXIS);
//this function is called from a protected one that constructs the anEntry, makes sure it should be added, and does a synchronize on panelVector
private void addEntry(MySubpanel anEntry)
  if(anEntry != null)
    try
      if(panelVector.add(anEntry))
        Collections.sort(panelVector);
        myTitlesVector.add(anEntry.title);
        Collections.sort(myTitlesVector);
        boxPanel.removeAll();
        for(int i = 0; i < panelVector.size(); i++)
          boxPanel.add(panelVector.get(i));
    catch (IllegalStateException isex)
      //couldn't add it
}So what's the problem?
Well, clicking the "accept" button I mentioned in the first post pops up a dialogue frame, which when the user OKs tells the server and other places in client that it was accepted. But when that dialogue box goes away the focus comes back to the main client frame. Well, that kicks off that sequence of calls in the event queue I put in the first post. If it just so happens that that topmost call is being performed on this panel containing the Box after the Box has gotten the removeAll() call, but before it's been filled back up to full, one or more of the MySubpanels will have a null for a parent, which causes the LayoutComparator to throw a ClassCastException.
So, I guess my question would be, is there a better way to maintain order in the Box (one in which the components stay in there, but are just moved around)? I can't pass the Box itself to Collections. Is there a way to move components around what order they are in right on the Box?
Thanks!