GUI freezes randomly

Question

I am writing a program which communicates with a CLIPS database using JClips library (generally the programs asks some questions and in the end prints an answer, kind of questionnaire). The program randomly freezes. I'll try to describe exactly the proble.
The main function calls the createAndShowGUI() method which shows an introduction screen with one button on it. The button starts the program. There are three main JPanels. First one with a TextArea (it shows the question) and two buttons (clear,confirm). Second one has a CardLayout with 4 cards (first one with radio buttons, another wict check box, one with text field, and one with a TextPane). When the program starts it adds an Observer and waits for CLIPS. Every message (in a specified format) I receive from CLIPS is precessed in the update mathod. Depending on what kind of message it is it shows apropriate card (radio buttons, check boxes, text field or text pane with an answer). If it is a question, when one selcts preferred answer (using for example radio box) and press the Confirm button a message with an answer is sent back to CLIPS. Then the database responds with another question or if it was th last one it sends an answer (a result of its deduction process).
This is the place wher the program freezes - after pressing the Confirm button. I really don't know the reason. It doesn't happen every time I run the program (about 15% probability that it hangs ;)) and it doesn't happen in a specific moment of the questionnaire.
This is my first Java program (and first object-oriented program) so this might be really basic problem.
The source code: http://avatar02.republika.pl/ExpertSystem.java

Answer 1

I've implemented these techniques and here is what it prints. This is the part of method responsible for printng.
System.out.println("\t" + stackEntry.getClassName()
          + "." + stackEntry.getMethodName() + " ["
          + stackEntry.getLineNumber() + "]");And this is part of a log that these debug methods print out:
Event [19297865] java.awt.event.MouseEvent is taking too much time on EDT (563)
AWT-EventQueue-1 / BLOCKED
     sun.awt.AppContext.get [-1]
     javax.swing.RepaintManager.currentManager [-1]
     javax.swing.RepaintManager.currentManager [-1]
     javax.swing.RepaintManager.currentManager [-1]
     javax.swing.JComponent.repaint [-1]
     java.awt.Component.repaint [-1]
     javax.swing.plaf.basic.BasicButtonListener.stateChanged [-1]
     javax.swing.AbstractButton.fireStateChanged [-1]
     javax.swing.AbstractButton$Handler.stateChanged [-1]
     javax.swing.DefaultButtonModel.fireStateChanged [-1]
     javax.swing.DefaultButtonModel.setPressed [-1]
     javax.swing.plaf.basic.BasicButtonListener.mouseReleased [-1]
     java.awt.Component.processMouseEvent [-1]
     javax.swing.JComponent.processMouseEvent [-1]
     java.awt.Component.processEvent [-1]
     java.awt.Container.processEvent [-1]
     java.awt.Component.dispatchEventImpl [-1]
     java.awt.Container.dispatchEventImpl [-1]
     java.awt.Component.dispatchEvent [-1]
     java.awt.LightweightDispatcher.retargetMouseEvent [-1]
     java.awt.LightweightDispatcher.processMouseEvent [-1]
     java.awt.LightweightDispatcher.dispatchEvent [-1]
     java.awt.Container.dispatchEventImpl [-1]
     java.awt.Window.dispatchEventImpl [-1]
     java.awt.Component.dispatchEvent [-1]
     java.awt.EventQueue.dispatchEvent [-1]
     TracingEventQueueJMX.dispatchEvent [18]
     java.awt.EventDispatchThread.pumpOneEventForFilters [-1]
     java.awt.EventDispatchThread.pumpEventsForFilter [-1]
     java.awt.EventDispatchThread.pumpEventsForHierarchy [-1]
     java.awt.EventDispatchThread.pumpEvents [-1]
     java.awt.EventDispatchThread.pumpEvents [-1]
     java.awt.EventDispatchThread.run [-1Could you please help me analyse this output? ;)
Thanks for replies.
Edited by: Avatar on Nov 29, 2007 10:26 AM