Fragments as static classes

Question

Just a brief question: In all the examples I've seen in the android documentation, fragments are static inner classes. Is that a requirement of Android? Or can they be set up as regular inner classes? Is there someone out there who understands the internals of Android enough to provide an answer?

From what I've read in the OCJP documentation, these static inner classes are not suppose to be classes at all, but are just static members of the class in which they are contained, just like any static method - such as main.

Your insights are appreciated.

Answer 1

Is that a requirement of Android? Or can they be set up as regular inner classes?

They cannot be regular (non-static) inner classes. Only an a instance of the outer class can create an instance of a regular inner class, and Android needs to recreate your fragments for you (e.g., on a configuration change). Fragments have to be either regular Java classes or static inner classes, and they need to have a public zero-argument constructor.

these static inner classes are not suppose to be classes at all, but are just static members of the class in which they are contained, just like any static method - such as main.

I have no idea how you came to that interpretation.