Java Swing Workers and comboBox issue

Question

I'm using Swing to build an application that uses a database. I have a weird problem that I don't understand how to solve.

In a certain panel, I have a comboBox which I want to populate with records using DB query. after finishing constructing the JPanel which hold the comboBox, I'm executing a Worker

private void populateLists(){
    GetSimpleRecordsWorker worker = new GetSimpleRecordsWorker(Tables.characters,panelLeftDetails);
    worker.execute();
}

Its doInBackground does a SELECT query and after getting the result - in the Worker's done() methods - updates the panel's model and calls the panel's refreshFromModel .

charI.setSimpleModel(simpleModel);
charI.refreshFromModel();

refreshFromModel does the following :

private void refreshFromSimpleModel(){
    charSelectCombo.removeAllItems();
    Pair[] pairs = simpleModel.getRecords();
    for (int i=0; i<pairs.length; i++){
        charSelectCombo.addItem(pairs[i]);
    }
    charSelectCombo.setSelectedItem(null);
}

Now, the problem is, after it finish refreshFromModel - the GUI stuck/freeze. I HAVE NO IDEA WHY! Weird is, in a different frame, I use the same methodology - and it works with no problems .

Also, if I try removeAll instead of removeAllItems it works but the ComboBox loses its arrow and acts weird.

I've taken the frame trace in the debugger - things like removeSourceEvent or Unsafe.park are there.

 GUI.GuiHandler at localhost:53547 (Suspended)  
Daemon System Thread [Attach Listener] (Suspended)  
Daemon System Thread [Signal Dispatcher] (Suspended)    
Daemon System Thread [Finalizer] (Suspended)    
    Object.wait(long) line: not available [native method]   
    ReferenceQueue<T>.remove(long) line: not available  
    ReferenceQueue<T>.remove() line: not available  
    Finalizer$FinalizerThread.run() line: not available 
Daemon System Thread [Reference Handler] (Suspended)    
    Object.wait(long) line: not available [native method]   
    Reference$Lock(Object).wait() line: 485 
    Reference$ReferenceHandler.run() line: not available    
Thread [AWT-Shutdown] (Suspended)   
    Object.wait(long) line: not available [native method]   
    Object.wait() line: 485 
    AWTAutoShutdown.run() line: not available   
    Thread.run() line: not available    
Daemon System Thread [Java2D Disposer] (Suspended)  
    Object.wait(long) line: not available [native method]   
    ReferenceQueue<T>.remove(long) line: not available  
    ReferenceQueue<T>.remove() line: not available  
    Disposer.run() line: not available  
    Thread.run() line: not available    
Daemon Thread [AWT-Windows] (Suspended) 
    WToolkit.eventLoop() line: not available [native method]    
    WToolkit.run() line: not available  
    Thread.run() line: not available    
Thread [AWT-EventQueue-0] (Suspended)   
    EventQueue.removeSourceEvents(Object, boolean) line: not available  
    WindowsComboBoxUI$WindowsComboBoxRenderer(Component).removeNotify() line: not available 
    WindowsComboBoxUI$WindowsComboBoxRenderer(Container).removeNotify() line: not available 
    WindowsComboBoxUI$WindowsComboBoxRenderer(JComponent).removeNotify() line: not available    
    CellRendererPane(Container).remove(int) line: not available 
    CellRendererPane(Container).remove(Component) line: not available   
    WindowsComboBoxUI(BasicComboBoxUI).getSizeForComponent(Component) line: not available   
    WindowsComboBoxUI(BasicComboBoxUI).getDisplaySize() line: not available 
    WindowsComboBoxUI(BasicComboBoxUI).getMinimumSize(JComponent) line: not available   
    AutoCompleteComboBox(JComponent).getMinimumSize() line: not available   
    FlowLayout.minimumLayoutSize(Container) line: not available 
    JPanel(Container).minimumSize() line: not available 
    JPanel(Container).getMinimumSize() line: not available  
    JPanel(JComponent).getMinimumSize() line: not available 
    BoxLayout.checkRequests() line: not available   
    BoxLayout.minimumLayoutSize(Container) line: not available  
    JPanel(Container).minimumSize() line: not available 
    JPanel(Container).getMinimumSize() line: not available  
    JPanel(JComponent).getMinimumSize() line: not available 
    BoxLayout.checkRequests() line: not available   
    BoxLayout.preferredLayoutSize(Container) line: not available    
    JPanel(Container).preferredSize() line: not available   
    JPanel(Container).getPreferredSize() line: not available    
    JPanel(JComponent).getPreferredSize() line: not available   
    BorderLayout.layoutContainer(Container) line: not available 
    JPanel(Container).layout() line: not available  
    JPanel(Container).doLayout() line: not available    
    JPanel(Container).validateTree() line: not available    
    JPanel(Container).validateTree() line: not available    
    JPanel(Container).validateTree() line: not available    
    JLayeredPane(Container).validateTree() line: not available  
    JRootPane(Container).validateTree() line: not available 
    JRootPane(Container).validate() line: not available 
    RepaintManager.validateInvalidComponents() line: not available  
    SystemEventQueueUtilities$ComponentWorkRequest.run() line: not available    
    InvocationEvent.dispatch() line: not available  
    EventQueue.dispatchEvent(AWTEvent) line: not available  
    EventDispatchThread.pumpOneEventForFilters(int) line: not available 
    EventDispatchThread.pumpEventsForFilter(int, Conditional, EventFilter) line: not available  
    EventDispatchThread.pumpEventsForHierarchy(int, Conditional, Component) line: not available 
    EventDispatchThread.pumpEvents(int, Conditional) line: not available    
    EventDispatchThread.pumpEvents(Conditional) line: not available 
    EventDispatchThread.run() line: not available   
Thread [DestroyJavaVM] (Suspended)  
Daemon System Thread [D3D Screen Updater] (Suspended)   
    Object.wait(long) line: not available [native method]   
    D3DScreenUpdateManager.run() line: not available    
    Thread.run() line: not available    
Daemon System Thread [TimerQueue] (Suspended)   
    Object.wait(long) line: not available [native method]   
    TimerQueue.run() line: not available    
    Thread.run() line: not available    
Thread [Thread-3] (Suspended)   
    Thread.sleep(long) line: not available [native method]  
    JDCConnectionPool$ConnectionReaper.run() line: 93   
Daemon Thread [SwingWorker-pool-1-thread-1] (Suspended) 
    Unsafe.park(boolean, long) line: not available [native method]  
    LockSupport.park(Object) line: not available    
    AbstractQueuedSynchronizer$ConditionObject.await() line: not available  
    LinkedBlockingQueue<E>.take() line: not available   
    ThreadPoolExecutor.getTask() line: not available    
    ThreadPoolExecutor$Worker.run() line: not available 
    Thread.run() line: not available    

Lot of thanks in advance.

Answer 1

its doInBackground does a SELECT query and after getting the result - updates the panel's model and calls the panel's refreshFromModel.

The DB query is done in the doInBackground().

The updating of the model need to be done in the process() method.

Read the section from the Swing tutorial on Concurrency for more information.

Answer 2

Adding 100,000 items to your combo box is probably the root of your problem.

You also have to wonder how one user could possibly deal with 100,000 items in a combo box.

JComboBox is normally not supposed to deal with such a big number of items.

One possible way to optimize your code would be to explicitly call setPrototypeDisplayValue() , this way, you avoid JComboBox checking the dimensions of ALL its model items to compute its own dimensions. That's probably the current reason why your system looks frozen.

Answer 3

I understand you are looking for autocomplete functionality with a massive amount of suggestions.

Perhaps you can have a look at the glazedlists library. Its core function is to provide observable lists, but it is very flexible. One of the things you can do is build a ComboBoxModel based on such a list and enable autocompletion for a combobox (through the AutoCompleteSupport class).

This approach may provide a way to avoid any ComboBox-related performance issues in addItem. That part would be moved into glazedlists.