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Old 07-11-2005, 11:40 PM   #1 (permalink)
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Default NullPointerException in a RichTextField - Help!

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Hi all,

I'm writing a simple multithreaded application for the BB 7290 (in simulator) with the latest RIM SDK and am experiencing an exception. Any ideas would be appreciated!

Here are the details:

1. My program has 3 background threads that perform processing.
2. My program has the usual main UI thread running a mainscreen object.
3. When one of my background threads wants to update a RichTextField in the mainscreen object, it uses the usual
synchronized(Application.getEventLock())
{ ... }
and inside the bracers calls a method of my mainscreen object to do so.
4. The method in the mainscreen object updates my richtext field using the following command:
m_myRichTextField.setText("Carey's value...");
5. None of the other background threads are accessing the
m_richTextField, nor is the mainscreen accesing the field except during construction or when called as discussed in step 3 above...
6. During a re-paint of the recently-changed rich-text field (described above), a NullPointerException is thrown. Here's the top of the stack:

RichTextField.getDisplayLineCount() Line 342
RichTextField.paint (Graphics) Line 607
Field.paintSelf(Graphics,boolean,int,int) Line 2857
Manager.paintChild(Graphics, Field) Line 1378
VerticalFieldManager.subpaint(Graphics) Line 364
...
MyApp.main(String[]) Line 19

7. This appears to be a synchronization issue, since its not consistently reproducable. It takes several attempts of starting/stopping the application (or switching between applications) to get it to throw. The issue only appears to happen after I update other fields in my mainscreen object (such as a list of items in the same vertical field manager). However, when updating this list of items, no changes are made whatsoever to the rich text field that's causing the exception.


Any help would be appreciated!

Thanks,

Carey
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