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urgent:Problem with action event of JButton  RSS feed

 
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hi freids,
i designing a chat server. When i click on send button to send the message to other users via chatserver i m getting lots of exceptions like-

at java.awt.LightweightDispatcher.dispatchEvent(Container.java:2125)
at java.awt.Container.dispatchEventImpl(Container.java:1200)
at java.awt.Window.dispatchEventImpl(Window.java:912)
at java.awt.Component.dispatchEvent(Component.java:2499)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:319)
etc.
what should i do for it.
its urgent. Please reply soon.
Richa.
 
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Maybe you could elaborate on what are the classes involved or a bit more details of things. It's quite hard to find out your problem.
Perhaps, maybe you are mixing lightweight & heavy weight components in your chat server?

------------------
Thank you.
- Simon See
simon-ivy@usa.net
-after office hours-
necro-mani-cide
 
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Could you post the complete list of exceptions? It looks like the primary exception is missing.

Originally posted by Richa Goyal:
hi freids,
i designing a chat server. When i click on send button to send the message to other users via chatserver i m getting lots of exceptions like-

at java.awt.LightweightDispatcher.dispatchEvent(Container.java:2125)
at java.awt.Container.dispatchEventImpl(Container.java:1200)
at java.awt.Window.dispatchEventImpl(Window.java:912)
at java.awt.Component.dispatchEvent(Component.java:2499)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:319)
etc.
what should i do for it.
its urgent. Please reply soon.
Richa.


 
Richa Goyal
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Posts: 18
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Originally posted by Simon See:
Maybe you could elaborate on what are the classes involved or a bit more details of things. It's quite hard to find out your problem.
Perhaps, maybe you are mixing lightweight & heavy weight components in your chat server?
I agree with you. Does mixing of lightweight & heavy weight components create some problem? what can be done for it?
I m using swing components and awt events in it.
The rest of errors are:
ERROR: java.lang.NullPointerException
java.lang.NullPointerException
at CRoom$1.actionPerformed(CRoom.java:58)
at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:14
50)
at javax.swing.AbstractButton$ForwardActionEvents.actionPerformed(Abstra
ctButton.java:1504)
at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel
.java:378)
at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:250
)
at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonL
istener.java:216)
at java.awt.Component.processMouseEvent(Component.java:3717)
at java.awt.Component.processEvent(Component.java:3546)
at java.awt.Container.proce
.java:378)
at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:250
)
at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonL
istener.java:216)
at java.awt.Component.processMouseEvent(Component.java:3717)
at java.awt.Component.processEvent(Component.java:3546)
at java.awt.Container.processEvent(Container.java:1164)
at java.awt.Component.dispatchEventImpl(Component.java:2595)
at java.awt.Container.dispatchEventImpl(Container.java:1213)
at java.awt.Component.dispatchEvent(Component.java:2499)
at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:2451
)
at java.awt.LightweightDispatcher.processMouseEvent(Container.java:2216)
at java.awt.LightweightDispatcher.dispatchEvent(Container.java:2125)
at java.awt.Container.dispatchEventImpl(Container.java:1200)
at java.awt.Window.dispatchEventImpl(Window.java:912)
at java.awt.Component.dispatchEvent(Component.java:2499)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:319)
at java.awt.EventDispatchThread.pumpOneEvent(EventDispatchThread.java:10
3)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:84)


 
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Hi Richa,
There is only one error happening. The rest of the lines are showing you a trace dump so you can see the current stack.
Usually a NullPointerException happens when you try and call a method of a null object. Inside your listener method make sure that all objects you are trying to use are non-null. For example:
if( ob != null )
{
// use it here because it is not null
ob.method();
}
Regards,
Manfred.
 
It is sorta covered in the JavaRanch Style Guide.
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