How to update screen in blackberry?

i am developing one app. and i a开发者_如何学运维m facing a problem related to updating the screen,which is already in stack.I tried to use myappscreen.invalidate() on button click,but it doesn't update screen.

Please help me to solve this problem.

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Is your screen the active screen?

To redraw the active screen, you should just need to call the invalidate() method to cause the screen to refresh.

Where are you calling invalidate() from? You cannot call invalidate() from a Timer thread unless you have got an eventlock.

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If you want to update screen then override activate() of UiApplication and write code in that which you want to update.