Encounter Null Pointer Exception when program is entered

[terry]

I encounter the following exception when my program is executed. Could
anyone tell me what has happened? The most trouble is that the error
does not always happen.

Thanks!

java.lang.NullPointerException
at sun.awt.windows.WInputMethod.dispatchEvent(WInputMethod.java:253)
at sun.awt.im.InputContext.dispatchEvent(InputContext.java:238)
at sun.awt.im.InputMethodContext.dispatchEvent(InputMethodContext.java:180)
at java.awt.Component.dispatchEventImpl(Component.java:3565)
at java.awt.Container.dispatchEventImpl(Container.java:1627)
at java.awt.Component.dispatchEvent(Component.java:3477)
at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:3483)
at java.awt.LightweightDispatcher.trackMouseEnterExit(Container.java:3323)
at java.awt.LightweightDispatcher.processMouseEvent(Container.java:3180)
at java.awt.LightweightDispatcher.dispatchEvent(Container.java:3128)
at java.awt.Container.dispatchEventImpl(Container.java:1613)
at java.awt.Window.dispatchEventImpl(Window.java:1606)
at java.awt.Component.dispatchEvent(Component.java:3477)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:456)
at java.awt.EventDispatchThread.pumpOneEventForHierarchy(EventDispatchThread.java:201)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:151)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:145)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:137)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:100)

 

[Thomas Weidenfeller]

I encounter the following exception when my program is executed. Could
anyone tell me what has happened? The most trouble is that the error
does not always happen.

Consider using a debugger. Also: http://www.physci.org/codes/sscce.jsp


/Thomas

 

[Roedy Green]

NullPointerException

see http://mindprod.com/jgloss/errormessages.html#NULLPOINTEREXCEPTION

 

[Sudsy]

I encounter the following exception when my program is executed. Could
anyone tell me what has happened? The most trouble is that the error
does not always happen.

Thanks!

java.lang.NullPointerException
at sun.awt.windows.WInputMethod.dispatchEvent(WInputMethod.java:253)
at sun.awt.im.InputContext.dispatchEvent(InputContext.java:238)
at sun.awt.im.InputMethodContext.dispatchEvent(InputMethodContext.java:180)
at java.awt.Component.dispatchEventImpl(Component.java:3565)
at java.awt.Container.dispatchEventImpl(Container.java:1627)
at java.awt.Component.dispatchEvent(Component.java:3477)
at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:3483)
at java.awt.LightweightDispatcher.trackMouseEnterExit(Container.java:3323)
at java.awt.LightweightDispatcher.processMouseEvent(Container.java:3180)

Can't tell more without seeing the source, but the stack trace seems
to indicate that it's attempting to process a mouse movement event.
Could it be that you've added a listener of null or the listener is
implemented in an object which has been gc'd?

 

[Lance Finney]

A Java Bug has been entered for this problem:

http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=5057174