Probem In Netbeans

Hello evey one i am getting the following exception on netbeans when going to run my gui swing frame form

[java.lang.NullPointerException
at org.openide.awt.CloseButtonTabbedPane.callSetTabCo mponentAt(CloseButtonTabbedPane.java:701)
at org.openide.awt.CloseButtonTabbedPane.insertTab(Cl oseButtonTabbedPane.java:176)
at javax.swing.JTabbedPane.addTab(JTabbedPane.java:68 4)
at javax.swing.JTabbedPane.add(JTabbedPane.java:701)
at org.netbeans.core.io.ui.IOWindow$IOWindowImpl.addT ab(IOWindow.java:320)
at org.netbeans.core.io.ui.IOWindow.add(IOWindow.java :97)
at org.openide.windows.IOContainer.add(IOContainer.ja va:150)
at org.netbeans.core.output2.Controller.createOutputT ab(Controller.java:113)
at org.netbeans.core.output2.Controller.performComman d(Controller.java:365)
at org.netbeans.core.output2.Controller.eventDispatch ed(Controller.java:97)
at org.netbeans.core.output2.IOEvent.dispatch(IOEvent .java:271)
at org.netbeans.core.output2.NbIO.post(NbIO.java:242)
at org.netbeans.core.output2.NbIOProvider.getIO(NbIOP rovider.java:119)
at org.netbeans.core.output2.NbIOProvider.getIO(NbIOP rovider.java:97)
at org.apache.tools.ant.module.run.TargetExecutor.exe cute(TargetExecutor.java:342)
at org.apache.tools.ant.module.api.AntTargetExecutor. execute(AntTargetExecutor.java:103)
at org.netbeans.modules.java.source.ant.ProjectRunner Impl.execute(ProjectRunnerImpl.java:125)
at org.netbeans.api.java.project.runner.JavaRunner.ex ecute(JavaRunner.java:270)
at org.netbeans.modules.java.j2seproject.J2SEActionPr ovider.bypassAntBuildScript(J2SEActionProvider.jav a:1282)
at org.netbeans.modules.java.j2seproject.J2SEActionPr ovider.access$1200(J2SEActionProvider.java:138)
at org.netbeans.modules.java.j2seproject.J2SEActionPr ovider$1Action.run(J2SEActionProvider.java:459)
at org.netbeans.api.java.source.ui.ScanDialog.runWhen ScanFinished(ScanDialog.java:150)
at org.netbeans.modules.java.j2seproject.J2SEActionPr ovider.invokeAction(J2SEActionProvider.java:535)
at org.netbeans.modules.project.ui.actions.ProjectAct ion.actionPerformed(ProjectAction.java:129)
at org.netbeans.modules.project.ui.actions.LookupSens itiveAction.actionPerformed(LookupSensitiveAction. java:166)
at javax.swing.AbstractButton.fireActionPerformed(Abs tractButton.java:1863)
at javax.swing.AbstractButton$Handler.actionPerformed (AbstractButton.java:2183)
at javax.swing.DefaultButtonModel.fireActionPerformed (DefaultButtonModel.java:377)
at javax.swing.DefaultButtonModel.setPressed(DefaultB uttonModel.java:232)
at javax.swing.AbstractButton.doClick(AbstractButton. java:302)
at javax.swing.plaf.basic.BasicMenuItemUI.doClick(Bas icMenuItemUI.java:1135)
at javax.swing.plaf.basic.BasicMenuItemUI$Handler.mou seReleased(BasicMenuItemUI.java:1176)
at java.awt.Component.processMouseEvent(Component.jav a:5907)
at javax.swing.JComponent.processMouseEvent(JComponen t.java:3321)
at java.awt.Component.processEvent(Component.java:567 2)
at java.awt.Container.processEvent(Container.java:196 0)
at java.awt.Component.dispatchEventImpl(Component.jav a:4346)
at java.awt.Container.dispatchEventImpl(Container.jav a:2018)
at java.awt.Component.dispatchEvent(Component.java:41 80)
at java.awt.LightweightDispatcher.retargetMouseEvent( Container.java:4222)
at java.awt.LightweightDispatcher.processMouseEvent(C ontainer.java:3886)
at java.awt.LightweightDispatcher.dispatchEvent(Conta iner.java:3816)
at java.awt.Container.dispatchEventImpl(Container.jav a:2004)
at java.awt.Window.dispatchEventImpl(Window.java:2101 )
at java.awt.Component.dispatchEvent(Component.java:41 80)
[catch] at java.awt.EventQueue.dispatchEvent(EventQueue.java: 599)
at org.netbeans.core.TimableEventQueue.dispatchEvent( TimableEventQueue.java:125)
at java.awt.EventDispatchThread.pumpOneEventForFilter s(EventDispatchThread.java:273)
at java.awt.EventDispatchThread.pumpEventsForFilter(E ventDispatchThread.java:183)
at java.awt.EventDispatchThread.pumpEventsForHierarch y(EventDispatchThread.java:173)
at java.awt.EventDispatchThread.pumpEvents(EventDispa tchThread.java:168)
at java.awt.EventDispatchThread.pumpEvents(EventDispa tchThread.java:160)
at java.awt.EventDispatchThread.run(EventDispatchThre ad.java:121)
]


i don't know what is the problem.

please tell me if any body know about this

thank you

Kind of hard to figure this out without code. I don't see the error as coming directly from your code and I have to wonder if you're taking precautions to run Swing from the EDT, the event dispatch thread.

thank you sir for reply

sir i am not understanding the EDT please tell me how i will use EDT.

Sir i am surprising that i have developeed 4 to 5 software on netbeans but this problem is coming for the first time. there is no problem in connection wit mysql.but status bar show continiously showing "Attempting to connect mysql server". even all the database of mysql server shows in netbeans and data intered in mysql by netbeans sql window.

But when i enter the data by gui means form it gives exception that sql client info exception
non registering driver.

i am getting irritating with this exception.
please sir help me if you hae the solution.

thank you