swing component exception

[angelin prema]

Hi All,
I have started the server and logged in with two client for the same server.
when I used to kill the session of another client from the first client,
my session of the client expired well,but I got swing component exception.
Exception is produced below....
2007-07-06 12:36:58,370 WARN [System.err] Exception in thread "AWT-EventQueue-0"
2007-07-06 12:36:58,370 WARN [System.err] java.lang.NullPointerException
2007-07-06 12:36:58,371 WARN [System.err] at javax.swing.plaf.basic.BasicTreeUI.paintRow(BasicTreeUI.java:1413)
2007-07-06 12:36:58,371 WARN [System.err] at javax.swing.plaf.basic.BasicTreeUI.paint(BasicTreeUI.java:1203)
2007-07-06 12:36:58,371 WARN [System.err] at javax.swing.plaf.metal.MetalTreeUI.paint(MetalTreeUI.java:152)
2007-07-06 12:36:58,371 WARN [System.err] at javax.swing.plaf.ComponentUI.update(ComponentUI.java:142)
2007-07-06 12:36:58,371 WARN [System.err] at javax.swing.JComponent.paintComponent(JComponent.java:742)
2007-07-06 12:36:58,371 WARN [System.err] at javax.swing.JComponent.paint(JComponent.java:1005)
2007-07-06 12:36:58,371 WARN [System.err] at javax.swing.JComponent.paintWithOffscreenBuffer(JComponent.java:4963)
2007-07-06 12:36:58,371 WARN [System.err] at javax.swing.JComponent.paintDoubleBuffered(JComponent.java:4916)
2007-07-06 12:36:58,371 WARN [System.err] at javax.swing.JComponent._paintImmediately(JComponent.java:4859)
2007-07-06 12:36:58,371 WARN [System.err] at javax.swing.JComponent.paintImmediately(JComponent.java:4666)
2007-07-06 12:36:58,371 WARN [System.err] at javax.swing.RepaintManager.paintDirtyRegions(RepaintManager.java:451)
2007-07-06 12:36:58,371 WARN [System.err] at javax.swing.SystemEventQueueUtilities$ComponentWorkRequest.run(SystemEventQueueUtilities.java:114)
2007-07-06 12:36:58,372 WARN [System.err] at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:209)
2007-07-06 12:36:58,372 WARN [System.err] at java.awt.EventQueue.dispatchEvent(EventQueue.java:461)
2007-07-06 12:36:58,372 WARN [System.err] at java.awt.EventDispatchThread.pumpOneEventForHierarchy(EventDispatchThread.java:242)
2007-07-06 12:36:58,372 WARN [System.err] at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:163)
2007-07-06 12:36:58,372 WARN [System.err] at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:157)
2007-07-06 12:36:58,372 WARN [System.err] at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:149)
2007-07-06 12:36:58,372 WARN [System.err] at java.awt.EventDispatchThread.run(EventDispatchThread.java:110)

Can anyone reply me the solution

[Nathan Pruett]

A "server" and a "session" are not normal parts of a Swing app... perhaps you could provide more information on what your program does.

[angelin prema]

I am getting this exception while updating the tree

[Nathan Pruett]

"updating the tree" can mean many things...

Are you manipulating the tree model by adding or removing nodes?

I could see this maybe causing a null pointer if you were updating the model outside of the event thread while the program was attempting to paint your tree... and suddenly trying to paint nodes that no longer exist.

Are you simply interacting with the tree by selecting, opening and closing nodes?

I could this maybe causing a null pointer if you have a custom tree node renderer and some bad data in some of your nodes - when you open them and try to paint them the first time, the bad data causes a null pointer exception while rendering.