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Working with GUIs throwing Exception in thread “main” java.lang.NullPointerException [duplicate]  RSS feed

 
Greenhorn
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I am working on a library management system program in Eclipse IDE. I am developing the GUIs but I am getting below nullPointerException error. I want to create a four JButton (Manage Material, Manage Patron, Load Data, Exit) button in my homepage and link with sub-menus.

The console error.




Below is the source code.

 
Rancher
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Android Eclipse IDE Java Java ME
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exitPanel is not initialized, leading to the exception.
 
Abdul Haq Sultani
Greenhorn
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Thanks Swastik! that was the issue. I never created an object of exitButton.
 
Marshal
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Don't make your class a subclass of JFrame. A library IS‑NOT‑A frame; a library appliication HAS‑A frame.
Please learn how to break lines. your line 81 for example is too long to read. There is useful information in the old Sun style guide.
 
It is sorta covered in the JavaRanch Style Guide.
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