AndroidArchitecture

Note

Samples here are still good enough, but there are much better and structured course in AndroidSchool.

Content

Most of us already know principles of Clean Architecture But to me these principles are more theoretical than practical. If we follow this principles directly we'll have about 6-9 classes for each screen (model, view, presenter, interactor, router, repository and so on). Most Android apps are pretty simple and doesn't require so many modules and classes. It can be simplified.

My suggestion is to use only these classes:

• Model is our POJO from server
• View is Activity or Fragment which interacts with the user and display all information
• Presenter is our most important object, which handles all business logic, handles lifecycle and manipulates view. Presenter uses repository to get data from the server or database.
• Repository is main layer between network and presenter
  • Sends requests directly to the remote API
  • Handles response, saves it to persistent storage and delivers to the presenter
  • Handles server error and trying to fix them (such as session expired) or deliver to the presenter in more readable way

In this architecutre presenter covers all the business logic and it's the only thing we need to test.

We should be able to mock repository using DI principles, e.g. static field and setter or Dagger2 or product flavors based IoC.

So, our final architecture will look like this:

Easy start

In this repository you can find samples for the described model. If you're new to Android Architecture, I suggest you to check the PopularMovies project, since it's very simple and easy to understand.

Complicated large sample with described architecture

If you're looking for more complicated architecture take a look at StackExchangeClient. It's rather large sample, with many screens and more - all presenters are tested with 100% coverage!

MVVM

MVVM for Android became more possible after release of DataBinding. Google also suggest architecture variant with DataBinding but again - it's very complicated and doesn't make sense.

The only variant when MVVM is acceptable is this architecture:

This architecture was implemented in PopularMoviesDataBinding sample. You can take a look on it and decide for yourself - is it good or not :) Personally I believe that MVP is much better.