Modularizing Android Applications

droidcon London 2017
droidcon Italy 2018

The recording of the talk at droidcon London is available here: http://uk.droidcon.com/skillscasts/10525-modularizing-android-applications#video

Most Android applications consist of one big, monolithic application project. As your application grows this single project can become harder and harder to manage, responsibilities become unclear and build times grow. Marvin will share how you can split up such an Android application into multiple, smaller modules. We will discuss how doing so might change the way you work in your applications codebase and how it can help in setting up clearer interfaces and responsibilities across teams. As modularizing an application changes the way you interact with the build system we will talk about how your build setup and times might change and how different build systems (such as Gradle, Buck and Bazel) interact with multiple modules.

Transcript

1. Modularizing Android Applications Marvin Ramin @Mauin
2. Modularizing Android Applications Marvin Ramin @Mauin
3. Motivations to modularize an application
4. Disclaimer
5. . !"" app # !"" build.gradle # $"" src # $"" main # !"" AndroidManifest.xml # !"" kotlin # # $"" com.some.app # # !"" Application.kt # # !"" login # # # !"" LoginActivity.kt # # # !"" LoginPresenter.kt # # # !"" LoginRepository.kt # # !"" content # # # !"" ContentActivity.kt # # # !"" ContentFragment.kt # # # !"" ContentDatabase.kt # # # !"" ApiClient.kt # # !"" feature3 # # !"" feature4 # # !"" apiclient # # !"" ... # # !"" ... # $"" res # !"" drawable # $"" ... # !"" build.gradle !"" gradle $"" settings.gradle
6. . !"" app # !"" build.gradle # $"" src # $"" main # !"" AndroidManifest.xml # !"" kotlin # # $"" com.some.app # # !"" Application.kt # # !"" login # # # !"" LoginActivity.kt # # # !"" LoginPresenter.kt # # # !"" LoginRepository.kt # # !"" content # # # !"" ContentActivity.kt # # # !"" ContentFragment.kt # # # !"" ContentDatabase.kt # # # !"" ApiClient.kt # # !"" feature3 # # !"" feature4 # # !"" apiclient # # !"" ... # # !"" ... # $"" res # !"" drawable # $"" ... # !"" build.gradle !"" gradle $"" settings.gradle
7. . !"" app # !"" build.gradle # $"" src # $"" main # !"" AndroidManifest.xml # !"" kotlin # # $"" com.some.app # # !"" Application.kt # # !"" login # # # !"" LoginActivity.kt # # # !"" LoginPresenter.kt # # # !"" LoginRepository.kt # # !"" content # # # !"" ContentActivity.kt # # # !"" ContentFragment.kt # # # !"" ContentDatabase.kt # # # !"" ApiClient.kt # # !"" feature3 # # !"" feature4 # # !"" apiclient # # !"" ... # # !"" ... # $"" res # !"" drawable # $"" ... # !"" build.gradle !"" gradle $"" settings.gradle
8. . !"" app # !"" build.gradle # $"" src # $"" main # !"" AndroidManifest.xml # !"" kotlin # # $"" com.some.app # # !"" Application.kt # # !"" login # # # !"" LoginActivity.kt # # # !"" LoginPresenter.kt # # # !"" LoginRepository.kt # # !"" content # # # !"" ContentActivity.kt # # # !"" ContentFragment.kt # # # !"" ContentDatabase.kt # # # !"" ApiClient.kt # # !"" feature3 # # !"" feature4 # # !"" apiclient # # !"" ... # # !"" ... # $"" res # !"" drawable # $"" ... # !"" build.gradle !"" gradle $"" settings.gradle
9. :app
10. :app login content apiclient
11. :app login content apiclient apply plugin: ‘com.android.application’
12. Single Module Application
13. Single Project Build
14. Monolith
15. TODO: Add image of interconnected codebase
16. Microservices in an Android App
17. Everything is visible No separation of concerns No clear APIs/responsibilities
18. Moving towards a modularized codebase
19. Look at your app
22. Look at your codebase
23. “Libraries” don’t have to be external
24. Multi-Project Build
25. :app login content apiclient apply plugin: ‘com.android.application’
26. :app login content apiclient apply plugin: ‘com.android.application’ settings.gradle include ':app'
27. :app login content :apiclient apply plugin: ‘com.android.application’
28. :app login content :apiclient apply plugin: ‘com.android.library’ apply plugin: ‘com.android.application’
29. :app login content :apiclient apply plugin: ‘com.android.library’ apply plugin: ‘com.android.application’ implementation project(':apiclient')
30. . !"" app # !"" build.gradle # $"" src # $"" main # !"" AndroidManifest.xml # !"" kotlin # # $"" com.some.app # # !"" Application.kt # # !"" login # # # !"" LoginActivity.kt # # # !"" LoginPresenter.kt # # # !"" AccountRepository.kt # # !"" content # # !"" apiclient # $"" res # !"" drawable # $"" … !"" build.gradle !"" gradle $"" settings.gradle
31. . !"" app # !"" build.gradle # $"" src # $"" main # !"" AndroidManifest.xml # !"" kotlin # # $"" com.some.app # # !"" Application.kt # # !"" login # # # !"" LoginActivity.kt # # # !"" LoginPresenter.kt # # # !"" AccountRepository.kt # # !"" content # # !"" apiclient # $"" res # !"" drawable # $"" … !"" build.gradle !"" gradle $"" settings.gradle
32. . !"" app # !"" build.gradle # $"" src # $"" main # !"" AndroidManifest.xml # !"" kotlin # # $"" com.some.app # # !"" Application.kt # # !"" login # # # !"" LoginActivity.kt # # # !"" LoginPresenter.kt # # # !"" AccountRepository.kt # # !"" content # $"" res # !"" drawable # $"" … !"" apiclient # !"" build.gradle # $"" src !"" build.gradle !"" gradle $"" settings.gradle
33. . !"" app # !"" build.gradle # $"" src # $"" main # !"" AndroidManifest.xml # !"" kotlin # # $"" com.some.app # # !"" Application.kt # # !"" login # # # !"" LoginActivity.kt # # # !"" LoginPresenter.kt # # # !"" AccountRepository.kt # # !"" content # $"" res # !"" drawable # $"" … !"" apiclient # !"" build.gradle # $"" src !"" build.gradle !"" gradle $"" settings.gradle settings.gradle
34. . !"" app # !"" build.gradle # $"" src # $"" main # !"" AndroidManifest.xml # !"" kotlin # # $"" com.some.app # # !"" Application.kt # # !"" login # # # !"" LoginActivity.kt # # # !"" LoginPresenter.kt # # # !"" AccountRepository.kt # # !"" content # $"" res # !"" drawable # $"" … !"" apiclient # !"" build.gradle # $"" src !"" build.gradle !"" gradle $"" settings.gradle settings.gradle include ‘:app’, ‘:apiclient’
35. . !"" app # !"" build.gradle # $"" src # $"" main # !"" AndroidManifest.xml # !"" kotlin # # $"" com.some.app # # !"" Application.kt # # !"" login # # # !"" LoginActivity.kt # # # !"" LoginPresenter.kt # # # !"" AccountRepository.kt # # !"" content # $"" res # !"" drawable # $"" … !"" modules # $"" apiclient # !"" build.gradle # $"" src !"" build.gradle !"" gradle $"" settings.gradle settings.gradle include ‘:app’, ‘:modules:apiclient’
36. :app login content :apiclient apply plugin: ‘com.android.library’ apply plugin: ‘com.android.application’ implementation project(':apiclient')
37. :app login content :apiclient apply plugin: ‘java-library’ apply plugin: ‘com.android.application’ implementation project(':apiclient')
38. :app login content :apiclient apply plugin: ‘kotlin’ apply plugin: ‘com.android.application’ implementation project(':apiclient')
39. Refactor —> Modularize
40. Refactor —> Modularize
41. :app login content :apiclient apply plugin: ‘kotlin’ apply plugin: ‘com.android.application’ implementation project(':apiclient')
42. :app :apiclient apply plugin: ‘kotlin’ apply plugin: ‘com.android.application’ implementation project(':apiclient') content login
43. :app :apiclient apply plugin: ‘kotlin’ apply plugin: ‘com.android.application’ implementation project(':apiclient') :login apply plugin: ‘com.android.library’ content
44. :app :apiclient apply plugin: ‘kotlin’ apply plugin: ‘com.android.application’ implementation project(':apiclient') :login apply plugin: ‘com.android.library’ implementation project(‘:login') content
45. :app :apiclient apply plugin: ‘kotlin’ apply plugin: ‘com.android.application’ implementation project(':apiclient') :login apply plugin: ‘com.android.library’ implementation project(‘:login') implementation project(‘:apiclient’) content
46. :app :apiclient apply plugin: ‘kotlin’ apply plugin: ‘com.android.application’ implementation project(':apiclient') :login apply plugin: ‘com.android.library’ implementation project(‘:login') implementation project(‘:apiclient’) content
47. :app :apiclient apply plugin: ‘kotlin’ apply plugin: ‘com.android.application’ implementation project(':apiclient') :login apply plugin: ‘com.android.library’ implementation project(‘:login') implementation project(‘:apiclient’) content :user
48. :app :apiclient apply plugin: ‘kotlin’ apply plugin: ‘com.android.application’ implementation project(':apiclient') :login apply plugin: ‘com.android.library’ implementation project(‘:login') implementation project(‘:apiclient’) content :user
49. :app :apiclient apply plugin: ‘kotlin’ apply plugin: ‘com.android.application’ implementation project(':apiclient') :login apply plugin: ‘com.android.library’ implementation project(‘:login') implementation project(‘:apiclient’) content :user :utils
50. :app :apiclient apply plugin: ‘kotlin’ apply plugin: ‘com.android.application’ implementation project(':apiclient') :login apply plugin: ‘com.android.library’ implementation project(‘:login') implementation project(‘:apiclient’) content :user :utils
51. :app :apiclient apply plugin: ‘kotlin’ apply plugin: ‘com.android.application’ implementation project(':apiclient') :login apply plugin: ‘com.android.library’ implementation project(‘:login') implementation project(‘:apiclient’) content :user :utils :rabbithole
52. :app :apiclient apply plugin: ‘kotlin’ apply plugin: ‘com.android.application’ implementation project(':apiclient') :login apply plugin: ‘com.android.library’ implementation project(‘:login') implementation project(‘:apiclient’) content :user :utils :rabbithole
53. :app :apiclient apply plugin: ‘kotlin’ apply plugin: ‘com.android.application’ implementation project(':apiclient') :login apply plugin: ‘com.android.library’ implementation project(‘:login') implementation project(‘:apiclient’) content :user :utils :rabbithole
54. :app login content apiclient apply plugin: ‘com.android.application’
55. :base content apiclient apply plugin: ‘com.android.library’ :app apply plugin: ‘com.android.application’ implementation project(‘:base') login
56. :base content apiclient apply plugin: ‘com.android.library’ :app apply plugin: ‘com.android.application’ :login implementation project(‘:base') apply plugin: ‘com.android.library’ implementation project(‘:base') implementation project(‘:login’)
57. :base content apply plugin: ‘com.android.library’ :app apply plugin: ‘com.android.application’ :login implementation project(‘:base') :apiclient apply plugin: ‘com.android.library’ apply plugin: ‘kotlin’ implementation project(‘:base') implementation project(‘:login’)
58. Different (sample) apps
59. :base apply plugin: ‘com.android.library’ :app :login apply plugin: ‘com.android.library’ :content apply plugin: ‘com.android.library’ apply plugin: ‘com.android.application’
60. :base apply plugin: ‘com.android.library’ :app :login apply plugin: ‘com.android.library’ :content apply plugin: ‘com.android.library’
61. :base apply plugin: ‘com.android.library’ :app :login apply plugin: ‘com.android.library’ :content apply plugin: ‘com.android.library’
62. :base apply plugin: ‘com.android.library’ :app :login apply plugin: ‘com.android.library’ :content apply plugin: ‘com.android.library’ :androidwear :instantapp :sample
63. Each module has a clear API
64. Each module has a clear API Clear responsibilities between teams
65. Each module has a clear API Clear responsibilities between teams Module maintenance goes up
66. Each module has a clear API Clear responsibilities between teams Module maintenance goes up Compile times go down
67. Why does it compile faster?
68. :app
69. :app Change
70. :app Change
71. :app :app Change
72. :app :app Change Change
73. :app :app Change Change
74. Declaring dependencies
75. compile someDependency
76. compile someDependency compile someDependency
77. compile someDependency api someDependency implementation someDependency compile someDependency
78. api implementation
79. api implementation :apiclient api ‘com.squareup:okhttp:3.9.0’ :apiclient implementation ‘com.squareup:okhttp:3.9.0’
80. api implementation :apiclient api ‘com.squareup:okhttp:3.9.0’ :apiclient implementation ‘com.squareup:okhttp:3.9.0’ :app :app
81. api implementation :apiclient api ‘com.squareup:okhttp:3.9.0’ :apiclient implementation ‘com.squareup:okhttp:3.9.0’ :app :app import com.squareup.OkHttpClient import com.squareup.OkHttpClient
82. api implementation :apiclient api ‘com.squareup:okhttp:3.9.0’ :apiclient implementation ‘com.squareup:okhttp:3.9.0’ :app :app import com.squareup.OkHttpClient import com.squareup.OkHttpClient
83. api implementation :apiclient api ‘com.squareup:okhttp:3.9.0’ :apiclient implementation ‘com.squareup:okhttp:3.9.0’ :app :app import com.squareup.OkHttpClient import com.squareup.OkHttpClient
84. Define your dependencies in one place
85. Define your dependencies in one place dependencies.gradle file
86. Define your dependencies in one place dependencies.gradle file Assure dependency versions are the same across all modules
87. Define your dependencies in one place dependencies.gradle file Assure dependency versions are the same across all modules Define core dependencies in a base module
88. // dependencies.gradle ext { androidBuildToolsVersion = '26.0.1' androidCompileSdkVersion = 26 androidMinSdkVersion = 23 androidTargetSdkVersion = 26 libraries = [ rxJava2 : "io.reactivex.rxjava2:rxjava:2.1.5", ... ] }
89. // dependencies.gradle ext { androidBuildToolsVersion = '26.0.1' androidCompileSdkVersion = 26 androidMinSdkVersion = 23 androidTargetSdkVersion = 26 libraries = [ rxJava2 : "io.reactivex.rxjava2:rxjava:2.1.5", ... ] } // build.gradle android { compileSdkVersion androidCompileSdkVersion buildToolsVersion androidBuildToolsVersion ... } dependencies { implementation libraries.rxJava2 }
90. apply plugin: “com.android.library” android { compileSdkVersion versions.compileSdk defaultConfig { minSdkVersion versions.minSdk targetSdkVersion versions.targetSdk versionCode 1 versionName "1.0" testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner" } buildTypes { release { minifyEnabled false proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro' } } }
91. apply plugin: “com.android.library” android { compileSdkVersion versions.compileSdk defaultConfig { minSdkVersion versions.minSdk targetSdkVersion versions.targetSdk versionCode 1 versionName "1.0" testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner" } buildTypes { release { minifyEnabled false proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro' } } } my-base-library.gradle:
92. // ./module/build.gradle apply from: “my-base-library.gradle” dependencies { … }
93. Centralize (some) resources
94. Centralize (some) resources colors, dimens, strings, …
95. Testing
96. Dependency Injection
97. @Component(modules = { ApplicationModule.class, ApiClientModule.class // <- comes from the :apiclient module }) public interface ApplicationComponent { }
98. Navigation
99. :base apply plugin: ‘com.android.library’ :app apply plugin: ‘com.android.application’ :login apply plugin: ‘com.android.library’ :content apply plugin: ‘com.android.library’
100. :base apply plugin: ‘com.android.library’ :app apply plugin: ‘com.android.application’ :login apply plugin: ‘com.android.library’ :content apply plugin: ‘com.android.library’ ?
101. Start writing new components in separate modules
102. Start writing new components in separate modules Identify core modules
103. Start writing new components in separate modules Identify core modules Make a plan and extract slowly
104. Start writing new components in separate modules Identify core modules Make a plan and extract slowly Enjoy the multi-module world
105. Thank you!
106. Thank you! github.com/Mauin twitter.com/@Mauin