/kotlin-sample-app

📚 Android Sample App using modular, clean, scalable, testable Architecture written in Kotlin following the best practices with Jetpack.

Primary LanguageKotlinApache License 2.0Apache-2.0

Kotlin Sample App (work-in-progress 👷🔧️👷‍♀️⛏)

CircleCI Codecov Codacy CodeFactor Kotlin Version Gradle API License

Kotlin Sample App is a sample project that presents modern, 2019 approach to Android application development using Kotlin and latest tech-stack.

The goal of the project is to demonstrate best practices, provide a set of guidelines, and present modern Android application architecture that is modular, scalable, maintainable and testable. This application may look simple, but it has all of these small details that will set the rock-solid foundation of the larger app suitable for bigger teams and long application lifecycle management.

Table of Contents

Development

Environment setup

First off, you require the latest Android Studio 3.5 (or newer) to be able to build the app.

You need to supply API keys for the various services the app uses. That is currently Marvel and Fabric (Crashlytics). You can find information about how to gain access via these relevant links.

When you obtain the keys, you can provide them to the app by putting the following in the local.properties project root file:

#Marvel API KEYS
marvel.key.public = <insert>
marvel.key.private = <insert>

#Fabric API KEYS
fabric.key = <insert>
fabric.secret = <insert>

Moreover, to sign your app for release you should generate an upload key and keystore following the official documentation. Append the information used to generate it into local.properties project root file following the structure:

#Signing Config
signing.key.alias = <insert>
signing.key.password = <insert>
signing.store.file = <insert>
signing.store.password = <insert>

Code style

To maintain the style and quality of the code, are used the bellow static analysis tools. All of them use properly configuration and you find them in the project root directory .{toolName}.

Tools Config file Check command Fix command
detekt /.detekt ./gradlew detekt -
ktlint - ./gradlew ktlint ./gradlew ktlintFormat
spotless /.spotless ./gradlew spotlessCheck ./gradlew spotlessApply
lint /.lint ./gradlew lint -

All these tools are integrated in pre-commit git hook, in order ensure that all static analysis and tests passes before you can commit your changes. To skip them for specific commit add this option at your git command:

git commit --no-verify

The pre-commit git hooks have exactly the same checks as CircleCI and are defined in this script. This step ensures that all commits comply with the established rules. However the continuous integration will ultimately be validated that the changes are correct.

Design

App support different screen sizes and the content has been adapted to fit for mobile devices and tablets. To do that, it has been created a flexible layout using one or more of the following concepts:

In terms of design has been followed recommendations android material design comprehensive guide for visual, motion, and interaction design across platforms and devices. Granting the project in this way a great user experience (UX) and user interface (UI). For more info about UX best practices visit link.

Moreover, has been implemented support for dark theme with the following benefits:

  • Can reduce power usage by a significant amount (depending on the device’s screen technology).
  • Improves visibility for users with low vision and those who are sensitive to bright light.
  • Makes it easier for anyone to use a device in a low-light environment.
Mode Characters list Characters favorite Character detail
Light
Dark

Architecture

//TODO

Build variants

The application has different product flavours: Dev, QA, Prod. Each variant has a specific target environment and to make easier to distinguish them the app uses a specific icon colour for debug and release build variant with descriptive app name. In this case and given that it's a sample, all variants have the same Marvel API endpoint. But the idea is to have different environments target for Development and QA respectively, what doesn't affect the production environment. This is applicable to any tool, platform, service what is being used. For more information about build variant, check this link.

Types DEV QA PROD
Debug


MarvelDEV


MarvelQA


Marvel
Release


MarvelDEV


MarvelQA


Marvel

Documentation

The documentation is generated following KDoc language (the equivalent of Java's JavaDoc) via documentation engine for Kotlin Dokka.

To consult it check this link or open the project /docs directory.

Tech-stack

This project takes advantage of many popular libraries, plugins and tools of the Android ecosystem. Most of the libraries are in the stable version, unless there is a good reason to use non-stable dependency.

Dependencies

  • Jetpack:
    • Android KTX - provide concise, idiomatic Kotlin to Jetpack and Android platform APIs.
    • AndroidX - major improvement to the original Android Support Library, which is no longer maintained.
    • Benchmark - handles warmup, measures your code performance, and outputs benchmarking results to the Android Studio console.
    • Data Binding - allows you to bind UI components in your layouts to data sources in your app using a declarative format rather than programmatically.
    • Lifecycle - perform actions in response to a change in the lifecycle status of another component, such as activities and fragments.
    • LiveData - lifecycle-aware, meaning it respects the lifecycle of other app components, such as activities, fragments, or services.
    • Navigation - helps you implement navigation, from simple button clicks to more complex patterns, such as app bars and the navigation drawer.
    • Paging - helps you load and display small chunks of data at a time. Loading partial data on demand reduces usage of network bandwidth and system resources.
    • Room - persistence library provides an abstraction layer over SQLite to allow for more robust database access while harnessing the full power of SQLite.
    • ViewModel - designed to store and manage UI-related data in a lifecycle conscious way. The ViewModel class allows data to survive configuration changes such as screen rotations.
  • Coroutines - managing background threads with simplified code and reducing needs for callbacks.
  • Dagger2 - dependency injector for replacement all FactoryFactory classes.
  • Retrofit - type-safe HTTP client.
  • Coil - image loading library for Android backed by Kotlin Coroutines.
  • Moshi - makes it easy to parse JSON into Kotlin objects.
  • Timber - a logger with a small, extensible API which provides utility on top of Android's normal Log class.
  • Stetho - debug bridge for applications via Chrome Developer Tools.
  • and more...

Test dependencies

  • UIAutomator - a UI testing framework suitable for cross-app functional UI testing across system and installed apps.
  • Espresso - to write concise, beautiful, and reliable Android UI tests
  • Robolectric - industry-standard unit testing framework for Android.
  • JUnit - a simple framework to write repeatable tests. It is an instance of the xUnit architecture for unit testing frameworks.
  • Mockito - most popular Mocking framework for unit tests written in Java.
  • Mockk - provides DSL to mock behavior. Built from zero to fit Kotlin language.
  • AndroidX - the androidx test library provides an extensive framework for testing Android apps.
  • and more...

Plugins

  • Ktlint - an anti-bikeshedding Kotlin linter with built-in formatter.
  • Detekt - a static code analysis tool for the Kotlin programming language.
  • Spotless - a code formatter can do more than just find formatting errors.
  • Versions - make easy to determine which dependencies have updates.
  • SafeArgs - generates simple object and builder classes for type-safe navigation and access to any associated arguments.
  • Jacoco - code coverage library
  • and more...

Resources

Projects

This is project is a sample, to inspire you and should handle most of the common cases, but obviously not all. If you need to take a look at additional resources to find solutions for your project, visit these interesting projects:

Articles

A collection of very interesting articles related last android community tendencies and recommendations for start to take in consideration for your current/next project:

Libraries

The open-source community create and maintains tons of awesome libraries making your job more easy, giving the opportunity to use them in your developments. Here are a very important collection of them:

Best practices

Avoid reinventing the wheel by following these guidelines:

Codelabs

Google Developers Codelabs provide a guided, tutorial, hands-on coding experience. Most codelabs will step you through the process of building a small application, or adding a new feature to an existing application. They cover a wide range of android concepts to learn and practice:

Contributions

All contributions are welcome! Please feel free to post questions, recommendations, ideas, bugs by create new issue following the template or if you want create directly new pull request.

License

Copyright 2019 vmadalin.com

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

   http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.