Snowball

It is a sample application which is desired as a showcase for how a clean Android Project should. It's still small and simple and need a lot of help to make it better. Please help me build it better and better. Cheers!

Objectives

Biggest goal of this project is create a good sample Android project which has good architecture and quality. It is heavy inspired of two great projects Android Clean Architecture and Quality Matters. Kudos Fernando Cejas and Artem Zinnatullin for their great jobs.

Outline

• Application functionality
• Application architecture design
• Conclusion

Application functionality

• Download list of items from rest api: API.
• Displays items as a list.
• Display images from item

Application architecture design

• General Architecture
• Dependency Injection
• Reactive framework
• Model-View-Presenter(MVP)
• Other practices

Architecture

I follow Clean Architecture in this project. I structure the project into 3 layers (3 packages):

Presentation package

This is presentation layer, its responsibility is to present data model into view which user interact with.

Domain package

This is business layer, we can look at this package and understand what application does. This module is Java module and it dependent with Android Framework.

Data package

This is data layer, its responsibility is loading data and caching data. All data comes from here. Other layers do not to care about where data is come from, they just ask Data layer to get data.

Layer rules:

Each layer expose its interfaces to another layers. They may dependent on other's abstraction not implementation that mean no layer knows other layers details.

Dependency Injection

This sample uses dependency inject(DI) (Dagger 2) to avoid boilerplate code and make project clean and follow Single Responsibility principle. Furthermore, DI give us power to create multiple build types for project. For example, this project has two build type: Release and Debug. For Debug build we have a lot of debug tools(such as: Logging, Stetho, LeakCanary) which should not contain in Release build. Without DI it's really hard to make it.

Reactive Framework

This project uses reactive programming(RxJava) for async job as well as app flow.

Model-View-Presenter(MVP)

This project uses my small library Nimble as an MVP library. You can read more about MVP here: MVP best practices.

Other practices

I try hard to follow SOLID in this project. It makes the application easier to maintain, test, and change. When using external dependencies (libraries), I prefer to write a wrapper interface for them, and hide all their implementations from my application. For example: Image caching library wrapper or Fake analytics tool library.