Why cleaning in Eclipse can cause error messages?

I cleaned my project in Eclipse and because of that, I think, I started to get the following error message:

a开发者_JS百科t check.GameWindow$12.run(MyWindow.java:1253)
at java.awt.event.InvocationEvent.dispatch(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)

So, I would like to ask why cleaning can cause error messages? I mean, the code before and after the cleaning is the same. Why it works differently before and after the cleaning.

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In my opinion, something has changed in your code that you are not aware of. When you clean your project, the only thing Eclipse does is to delete .class files in your build/ directory and recompile all sources.

If you don't have compilation errors, there should be something wrong in an an anonymous inner class in check.GameWindow.

Please check.