calling invokeAndWait from the EDT

Question

I have a problem following from my previous problem. I also have the code SwingUtillities.invokeAndWait somewhere else in the code base, but when I remove this the gui does not refresh. If I dont remove it the error I get is:

Exception in thread "AWT-EventQueue-0" java.lang.Error: Cannot call invokeAndWait from the event dispatcher thread
 at java.awt.EventQueue.invokeAndWait(Unknown Source)
 at javax.swing.SwingUtilities.invokeAndWait(Unknown Source)
 at game.player.humanplayer.model.HumanPlayer.act(HumanPlayer.java:69)

The code in HumanPlayer.act is:

public Action act(final Action[] availiableActions) {
  try {

   SwingUtilities.invokeAndWait(new Runnable() {
    @Override
    public void run() {
     gui.update(availiableActions);
    }
   });
  }
  catch (InterruptedException e) {
   e.printStackTrace();
  } catch (InvocationTargetException e) {
   e.printStackTrace();
  }

  synchronized(performedAction){
   while(!hasPerformedAction()){
    try {
     performedAction.wait();
    } catch (InterruptedException e) {
     e.printStackTrace();
    }
   }
   setPerformedAction(false); 
  }

  return getActionPerfomed();
 }

Image of threads when in debug as screen doesn't paint: alt text http://img684.imageshack.us/img684/6669/69288941.png

Text version of stack:

ui.startup.LoginScreen at localhost:51050
 -> Deamon Thread [AWT-Windows] (Running)
 -> Thread [AWT-Shutdown] (Running)
 -> Thread [AWT-EventQueue-0] (Running)
 -> Thread [DestroyJavaVM] (Running)

Answer 1

The answer was instead of making the call

new GameInitializer(userName, player, Constants.BLIND_STRUCTURE_FILES.get(blindStructure), handState);

from the EDT, make it execute on a new (non EDT) thread so that later when invokeAndWait is called it functions as correctly as the thread running that command is not the EDT. The amended code is as follows:

Thread t = new Thread(new Runnable() {
    @Override
    public void run() {
       new GameInitializer(userName, player, Constants.BLIND_STRUCTURE_FILES.get(blindStructure), handState);       
    }

   });
t.start();

Answer 2

invokeAndWait() is meant to be called from the non-GUI thread. It sends a Runnable object to the GUI thread where it will be executed.

There's no point in sending a Runnable object from the GUI-thread to itself. It has the same effect as calling run() on the Runnable object directly.

Answer 3

You can check before if your current calling thread is already the event dispatcher:

private void syncExec(final Runnable r) {
    try {
        if (EventQueue.isDispatchThread()) r.run();
        else EventQueue.invokeAndWait(r);
    } catch (final Exception e) {
        Throws.throwRuntime(e);
    }
}

Note that SwingUtilities.invokeAndWait(Runnable) simply delegates to the EventQueue.