I've read and tested much about MVP patterns in Android, but I'm here to ask your opinion about what could be the best practice if I want to respect both the "Dependency Rule" and the MVP pattern.
How it is explained into many articles (see this link: http://fernandocejas.com/2014/09/03/architecting-android-the-clean-way/), our application must be divided into layers and only an outer layer can instantiate and use an inner layer. The inner layer receive all parameters (Variables, contexts, Views, etc.) and return response or use callbacks etc.
It is also a good practice to isolate the layers the more you can, through using interfaces and calling the interfaces instead of classes directly. (see the link: http://www.tinmegali.com/en/model-view-presenter-mvp-in-android-part-2/). In the link above the author specifies he doesn't use callback methods but interfaces to move from an inner layer to an outer layer (not respecting the dependency rule).
My questions about this are two:
1) is it better to use interface for both the calling class (outer layer refers to the interface of the class called) and the called class (inner layer refers to the interface of the class calling), or is it only necessary in one direction, for instance only outer class refers to interface of inner one?
2) because the external layer (the UI) creates all inner layers and through a simple screen rotation is destroyed and recreated, is it better (for the memory leak) to save the state (when it's needed), destroy inner classes and processes, and recreate them, or to istantiate in a static way (through Singleton or as instances of a class which extends Application class) all the classes which need to "survive" to rotation screen? Thanks to everyone!
