A sample Kotlin app which was built with modular structure, Kotlin DSL, Kotlin Coroutines, TDD and MVVM patterns.
This project is a sample that presents modern, the recent approach to Android application development using Kotlin and latest technology 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.
:boom: Powered by TvMaze.
First off, you require the latest Android Studio 3.5 (or newer) to be able to build the app.
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>
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 | /config/detekt | ./gradlew detekt |
./gradlew detektFormat or ./gradlew detektAll |
ktlint | - | ./gradlew ktlint |
./gradlew ktlintFormat |
spotless | /spotless | ./gradlew spotlessCheck |
./gradlew spotlessApply |
lint | each module | ./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.
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:
The architecture of the application is based, apply and strictly complies with each of the following 5 points:
Modules are collection of source files and build settings that allow you to divide a project into discrete units of functionality. In this case apart from dividing by functionality/responsibility, existing the following dependence between them:
The above graph shows the app modularisation:
:app
module depends on :base
, :data
, :domain
and :test-shared
:data
module depends on :base
and :test-shared
.:domain
module depends on :base
, :data
and :test-shared
:base
doesn’t have any dependency.The :app
module is an com.android.application, which is needed to create the app bundle. It is also responsible for initiating the dependency graph, play core and another project global libraries, differentiating especially between different app environments.
The :base
module is an com.android.library only contains code and resources which are shared between other modules. Reusing this way resources, layouts, views, and components in the different modules, without the need to duplicate code.
The :data
module is an com.android.library for serving network requests or accessing to the database. Providing the data source for the many features that require it.
The :domain
module is an com.android.library lays a bridge between data
and view layers. It performs any business logic getting data from data
module and serves to view.
The :test-shared
module is an com.android.library, basically contains test utilities that can be used by the different modules.
Ideally, ViewModels shouldn’t know anything about Android. This improves testability, leak safety and modularity. ViewModels have different scopes than activities or fragments. While a ViewModel is alive and running, an activity can be in any of its lifecycle states. Activities and fragments can be destroyed and created again while the ViewModel is unaware.
Passing a reference of the View (activity or fragment) to the ViewModel is a serious risk. Lets assume the ViewModel requests data from the network and the data comes back some time later. At that moment, the View reference might be destroyed or might be an old activity that is no longer visible, generating a memory leak and, possibly, a crash.
The communication between the different layers follow the above diagram using the reactive paradigm, observing changes on components without need of callbacks avoiding leaks and edge cases related with them.
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.
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.
Mainly on:
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:
A collection of very interesting articles related last android community tendencies and recommendations for start to take in consideration for your current/next project:
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:
Avoid reinventing the wheel by following these guidelines:
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:
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.
Copyright 2019 nuhkoca.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.