Does a member class have to be within the same source file?

Question

Hi there,
I have this application that extensively uses two classes. The main class setsup the GUI, and the second main class is responsible for handling all of the actions that arise from the GUI.
I could have done this by making all of my handler methods be of the first main class, but this class really is just for the GUI setup, the logic doesn't fit into this class' behaviour.
The class that handles the GUI actions is required to use the fields of the main class e.g. to get values of a text field. The problem is that since the class that handles the actions is getting very big, I would kind of like to move this class into a different source file - because currently it is a member class of the first one, so that it can access all of its fields.
Is there some way that I can move this handler class into another source file, and still have it access all of the fields of the main GUI class - without making the fields public, or using millions of get/set methods? Also, I can't use inheritance because the both the GUI class creates an instance of the handler class in its constructor, and so leads to an infinite loop when trying to instantiate the GUI class.
Can I ask.. would a static class or something be of use here? Do they exist? I'm confused as to how to do this without getting the mother of all source files (in size that is - nothing to do with cooking or baking).
- Anyway, thanks in advance for any help that you could give me -
BYEE, Edd.

Answer 1

You can't have an inner class that is not in the same source file. However, you could use package-protected (default) access to give another class in the same package access to things without making them public. Actually, that's how inner classes are actually compiled. Package-protected access is underused IMHO. It's a great tool that most people (including myself) are suspicious of at first.