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.

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.