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Java Development

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Posts: 3
Registered: ‎04-06-2012
My Device: Non BlackBerry user
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Push & Pop Screen Concept



When pushed the screens were pushed successfully from one class to another but when tried to retreive the first screen back again using popScreen it is giving NullPointerException.




Posts: 19,636
Registered: ‎07-14-2008
My Device: Not Specified

Re: Push & Pop Screen Concept

Remember that the Display stack is a stack.  So you push a screen onto the stack, and the new screen is displayed on top.  If you pop the current screen off the stack, then the screen underneath will be displayed.  So normally you will be popping the current screen using code like




And if your code looks like the above, it can't get a NPE from the screen reference!


Hope this sheds some light on your problem.  If not, then we will need to see the line of code that throws the NPE and tell us what is null (if it is not obvious).