问题:

I read this answer and undestood why I should keep names of my services, activities, and custom views. But should I keep my classes which derive from android.support.v4.app.Fragment?

I also took a look at the defualt Proguard config file %SDK_DIR%\sdk\tools\proguard\proguard-android.txt, and there were no rules regarding fragments.

回答1:

The main reason why you would need to keep a class, is because it is accessed via reflection.

Fragments are normally not accessed via reflection, so you don't have to keep them.

Except if you reference them directly in layout files (because parsing layout files uses reflection).

回答2:

As others have already pointed out, the main reason to keep UI elements like Fragments from being obfuscated is because they are referenced from other resources that are not processed by ProGuard, e.g. layout files.

If you would be using DexGuard you could also obfuscate Fragments and other UI classes as DexGuard will process all application resources together, allowing it to modify class names whereever they are used (except when used via reflection of course).