sliskiCode / TopStackOverflowUsers

It is a simple StackOverflow client that shows the top 20 users along with their details. The application is design to be used on phones and on tablets. On phones, we have a simple list and after selecting the user a screen with details pops up. On tablets, the application uses a master/detail approach.

Top StackOverflow Users

• Overview
• Architecture
• 3rd party libraries
• Known issues

Overview

It is a simple StackOverflow client that shows the top 20 users along with their details. The application is design to be used on phones and on tablets. On phones, we have a simple list and after selecting the user a screen with details pops up. On tablets, the application uses a master/detail approach.

Features

• Displaying list of users.
• Displaying user details page with necessary information.
• Can be used on phones and tablets.

Architecture

Packaging

The code is structured using "package by feature" approach. The main reason for such packaging is to imitate app domain structure into the code.

Model

Main business logic lives in the Model layer. Model is responsible for downloading data from Repository and combine them with network status. Repository is implemented on the top of Retrofit library that is configured to work with RxJava.

Reactive flow

RxJava was used to combine two main streams that Model logic defines. Network state and data from the endpoint. The reason behind using RxJava here was not multithreading but working with multiple streams.

View

Thanks to Android Data Binding mechanism Activity or Fragment acts as a Dummy View. It does not contain any presentation or render logic. View is only responsible for getting an instance of ViewModel and bind it to generated representation of xml layout(Binding). In some scenarios it also needs to do addition work but only related to gluing everything together or specific Android Framework stuff.

ViewModel

ViewModel is build on top of Android Architecture Components. It gives simplicity when it comes to screen rotation as it survives Fragment or Activity re-creation. Main responsibility of a ViewModel is to react to specific Model data stream and change state of UI. Updating ViewState is automatically translated to UI due data binding mechanism.

Dependency Inversion

There is no dependency injection framework used. For the simplicity of this application constructor injection(with default values) is the main approach to build lose coupling and testable code. Dagger 2 or Koin frameworks would not solve any problems. It would only introduce unnecessary complexity.

3rd party libraries

• Retrofit2 (Networking).
• RxJava2 (Working with streams).
• Glide (Downloading and caching images).
• Joda-Time for Android (Working with dates).
• Android Data Binding (MVVM helper).

Known issues

• Sometimes NetworkMonitor emits incorrect state when app is in the background.
• Lack of UI/Espresso tests for user journeys.