MVC pattern on Android

In Android you don't have MVC, but you have the following:

• You define your user interface in various XML files by resolution, hardware, etc.
• You define your resources in various XML files by locale, etc.
• You extend clases like ListActivity, TabActivity and make use of the XML file by inflaters.
• You can create as many classes as you wish for your business logic.
• A lot of Utils have been already written for you - DatabaseUtils, Html.

The actions, views and activities on Android are the baked-in way of working with the Android UI and are an implementation of the model–view–viewmodel (MVVM) pattern, which is structurally similar (in the same family as) model–view–controller.

To the best of my knowledge, there is no way to break out of this model. It can probably be done, but you would likely lose all the benefit that the existing model has and have to rewrite your own UI layer to make it work.

After some searching, the most reasonable answer is the following:

MVC is already implemented in Android as:

1. View = layout, resources and built-in classes like Button derived from android.view.View.
2. Controller = Activity
3. Model = the classes that implement the application logic

(This by the way implies no application domain logic in the activity.)

The most reasonable thing for a small developer is to follow this pattern and not to try to do what Google decided not to do.

PS Note that Activity is sometimes restarted, so it's no place for model data (the easiest way to cause a restart is to omit android:configChanges="keyboardHidden|orientation" from the XML and turn your device).

EDIT

We may be talking about MVC, but it will be so to say FMVC, Framework--Model--View--Controller. The Framework (the Android OS) imposes its idea of component life cycle and related events, and in practice the Controller (Activity/Service/BroadcastReceiver) is first of all responsible for coping with these Framework-imposed events (such as onCreate()). Should user input be processed separately? Even if it should, you cannot separate it, user input events also come from Android.

Anyway, the less code that is not Android-specific you put into your Activity/Service/BroadcastReceiver, the better.

There is no universally unique MVC pattern. MVC is a concept rather than a solid programming framework. You can implement your own MVC on any platform. As long as you stick to the following basic idea, you are implementing MVC:

• Model: What to render
• View: How to render
• Controller: Events, user input

Also think about it this way: When you program your model, the model should not need to worry about the rendering (or platform specific code). The model would say to the view, I don't care if your rendering is Android or iOS or Windows Phone, this is what I need you to render. The view would only handle the platform-specific rendering code.

This is particularly useful when you use Mono to share the model in order to develop cross-platform applications.