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Improving your Android Gradle Experience with Kotlin

Improving your Android Gradle Experience with Kotlin

The talk was given at Kotlin Everywhere Hamburg, August 2019 - https://www.eventbrite.co.uk/e/kotlineverywhere-hamburg-tickets-64993039932

The talk involved sharing tips about how we can optimize Gradle for our Android projects. The talk shares some approaches using the standard Groovy DSL for customizing Gradle build system, and takes it into using Kotlin DSL and also writing custom Gradle plugins in Kotlin.

Resources:
* https://handstandsam.com/2019/03/12/sharing-gradle-configuration-in-multi-module-android-projects/
* https://segunfamisa.com/posts/android-gradle-extra-properties
* https://gradle.com/blog/getting-started-with-gradle-kotlin-dsl/
* https://github.com/gradle/kotlin-dsl
* Build Bigger, Better: Gradle for Large Projects (Google I/O'19) - https://www.youtube.com/watch?v=sQC9-Rj2yLI

9ab0b3b080e75e0c03a0c643333f8b93?s=128

Segun Famisa

August 30, 2019
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Transcript

  1. None
  2. @segunfamisa

  3. Outline • Introduction • Scenarios & improvements #0, #1, #2

    • Taking it a step further with Kotlin DSL • buildSrc • Migrating build scripts to Kotlin DSL from Groovy DSL • Kotlin DSL improvements • Custom Plugins • Resources
  4. Improving your gradle experience

  5. #0

  6. Small project, single or few modules #0

  7. // <app> build.gradle apply plugin: 'com.android.application' ... dependencies { ...

    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.3.31" implementation "io.reactivex.rxjava2:rxjava:2.2.5" } #0
  8. // <networking-lib> build.gradle apply plugin: 'kotlin' ... dependencies { ...

    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.3.31" implementation "io.reactivex.rxjava2:rxjava:2.2.5" } // <app> build.gradle apply plugin: 'com.android.application' ... dependencies { ... implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.3.31" implementation "io.reactivex.rxjava2:rxjava:2.2.5" } #0
  9. // <app> build.gradle apply plugin: 'com.android.application' ... dependencies { ...

    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.3.31" implementation "io.reactivex.rxjava2:rxjava:2.2.5" } // <networking-lib> build.gradle apply plugin: 'kotlin' ... dependencies { ... implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.3.31" implementation "io.reactivex.rxjava2:rxjava:2.2.5" } #0
  10. #0 // <app> build.gradle apply plugin: 'com.android.application' ... dependencies {

    ... implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.3.31" implementation "io.reactivex.rxjava2:rxjava:2.2.5" } // <networking-lib> build.gradle apply plugin: 'kotlin' ... dependencies { ... implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.3.31" implementation "io.reactivex.rxjava2:rxjava:2.2.5" } Managing dependencies versions becomes tedious
  11. #0 - solution

  12. #0 - solution Solving the duplication problem with Gradle extra

    (ext) properties feature
  13. // dependencies.gradle ext { ... libraries = [ rxJavaVersion :

    '2.2.5' rxAndroidVersion : '2.1.0' kotlinVersion : '1.3.31' ] } 1. Externalize dependencies
  14. 1. Externalize dependencies 2. Apply dependencies.gradle to root project //

    root build.gradle buildScript {...} allprojects {...} apply from: 'relative/path/to/dependencies.gradle'
  15. 1. Externalize dependencies 2. Apply dependencies.gradle to root project 3.

    Reference the dependencies in the build.gradle files // <app> build.gradle dependencies { ... def libs = rootProject.ext.libraries implementation "org.jetbrains.kotlin:...:$libs.kotlinVersion" implementation "io.reactivex.rxjava2:rxjava:$libs.rxJavaVersion" }
  16. 1. Externalize dependencies 2. Apply dependencies.gradle to root project 3.

    Reference the dependencies in the build.gradle files // <app> build.gradle dependencies { implementation "org.jetbrains.kotlin:...:$libs.kotlinVersion" implementation "io.reactivex.rxjava2:rxjava:$libs.rxJavaVersion" } // <networking-lib> build.gradle dependencies { ... def libs = rootProject.ext.libraries implementation "org.jetbrains.kotlin:...:$libs.kotlinVersion" implementation "io.reactivex.rxjava2:...:$libs.rxJavaVersion" }
  17. 1. Externalize dependencies 2. Apply dependencies.gradle to root project 3.

    Reference the dependencies in the build.gradle files // <app> build.gradle dependencies { implementation "org.jetbrains.kotlin:...:$libs.kotlinVersion" implementation "io.reactivex.rxjava2:rxjava:$libs.rxJavaVersion" } // <networking-lib> build.gradle dependencies { ... def libs = rootProject.ext.libraries implementation "org.jetbrains.kotlin:...:$libs.kotlinVersion" implementation "io.reactivex.rxjava2:...:$libs.rxJavaVersion" }
  18. • Managing/updating versions of dependencies is now easier - just

    need to change in one place • Still has the problem of duplication of dependencies
  19. #1

  20. #1 • Fairly complex projects • Multiple modules • You

    will find a lot of repetitions in the dependencies
  21. #1 // <login> build.gradle dependencies { implementation fileTree(dir: 'libs', include:

    ['*.jar']) implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version" implementation "io.reactivex.rxjava2:rxjava:$rxJavaVersion" testImplementation "junit:junit:$libs.jUnitVersion" ... // other dependencies }
  22. #1 // <login> build.gradle dependencies { implementation fileTree(dir: 'libs', include:

    ['*.jar']) implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version" implementation "io.reactivex.rxjava2:rxjava:$rxJavaVersion" testImplementation "junit:junit:$libs.jUnitVersion" ... // other dependencies } // <profile> build.gradle dependencies { implementation fileTree(dir: 'libs', include: ['*.jar']) implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version" implementation "io.reactivex.rxjava2:rxjava:$rxJavaVersion" testImplementation "junit:junit:$libs.jUnitVersion" ... // other dependencies }
  23. #1 // <login> build.gradle dependencies { implementation fileTree(dir: 'libs', include:

    ['*.jar']) implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version" implementation "io.reactivex.rxjava2:rxjava:$rxJavaVersion" testImplementation "junit:junit:$libs.jUnitVersion" ... // other dependencies } // <profile> build.gradle dependencies { implementation fileTree(dir: 'libs', include: ['*.jar']) implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version" implementation "io.reactivex.rxjava2:rxjava:$rxJavaVersion" testImplementation "junit:junit:$libs.jUnitVersion" ... // other dependencies } // <search> build.gradle dependencies { implementation fileTree(dir: 'libs', include: ['*.jar']) implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version" implementation "io.reactivex.rxjava2:rxjava:$rxJavaVersion" testImplementation "junit:junit:$libs.jUnitVersion" ... // other dependencies }
  24. #1 // <login> build.gradle dependencies { implementation fileTree(dir: 'libs', include:

    ['*.jar']) implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version" implementation "io.reactivex.rxjava2:rxjava:$rxJavaVersion" testImplementation "junit:junit:$libs.jUnitVersion" ... // other dependencies } // <profile> build.gradle dependencies { implementation fileTree(dir: 'libs', include: ['*.jar']) implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version" implementation "io.reactivex.rxjava2:rxjava:$rxJavaVersion" testImplementation "junit:junit:$libs.jUnitVersion" ... // other dependencies } // <search> build.gradle dependencies { implementation fileTree(dir: 'libs', include: ['*.jar']) implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version" implementation "io.reactivex.rxjava2:rxjava:$rxJavaVersion" testImplementation "junit:junit:$libs.jUnitVersion" ... // other dependencies } // <core> build.gradle dependencies { implementation fileTree(dir: 'libs', include: ['*.jar']) implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version" implementation "io.reactivex.rxjava2:rxjava:$rxJavaVersion" testImplementation "junit:junit:$libs.jUnitVersion" ... // other dependencies }
  25. #1 // <login> build.gradle dependencies { implementation fileTree(dir: 'libs', include:

    ['*.jar']) implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version" implementation "io.reactivex.rxjava2:rxjava:$rxJavaVersion" testImplementation "junit:junit:$libs.jUnitVersion" ... // other dependencies } // <profile> build.gradle dependencies { implementation fileTree(dir: 'libs', include: ['*.jar']) implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version" implementation "io.reactivex.rxjava2:rxjava:$rxJavaVersion" testImplementation "junit:junit:$libs.jUnitVersion" ... // other dependencies } // <search> build.gradle dependencies { implementation fileTree(dir: 'libs', include: ['*.jar']) implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version" implementation "io.reactivex.rxjava2:rxjava:$rxJavaVersion" testImplementation "junit:junit:$libs.jUnitVersion" ... // other dependencies } // <core> build.gradle dependencies { implementation fileTree(dir: 'libs', include: ['*.jar']) implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version" implementation "io.reactivex.rxjava2:rxjava:$rxJavaVersion" testImplementation "junit:junit:$libs.jUnitVersion" ... // other dependencies } Problem: Repeated declarations of dependencies in so many modules
  26. #1 Solution: extract common/shared dependencies and apply to the modules

  27. 1. Extract common dependencies // shared-dependencies.gradle - contains all shared

    dependncies dependencies { implementation fileTree(dir: 'libs', include: ['*.jar']) implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version" implementation "io.reactivex.rxjava2:rxjava:$rxJavaVersion" ... testImplementation 'junit:junit:4.12' }
  28. 1. Extract common dependencies 2. Apply common dependencies to respective

    modules // <login> build.gradle apply from: “relative/path/to/shared-dependencies.gradle" ... dependencies { ... // other dependencies }
  29. 1. Extract common dependencies 2. Apply common dependencies to respective

    modules // <login> build.gradle apply from: “relative/path/to/shared-dependencies.gradle" ... dependencies { ... // other dependencies } // <profile> build.gradle apply from: “relative/path/to/shared-dependencies.gradle" ... dependencies { ... // other dependencies }
  30. 1. Extract common dependencies 2. Apply common dependencies to respective

    modules // <login> build.gradle apply from: “relative/path/to/shared-dependencies.gradle" ... dependencies { ... // other dependencies } // <profile> build.gradle apply from: “relative/path/to/shared-dependencies.gradle" ... dependencies { ... // other dependencies } // <search> build.gradle apply from: “relative/path/to/shared-dependencies.gradle" ... dependencies { ... // other dependencies }
  31. 1. Extract common dependencies 2. Apply common dependencies to respective

    modules // <login> build.gradle apply from: “relative/path/to/shared-dependencies.gradle" ... dependencies { ... // other dependencies } // <profile> build.gradle apply from: “relative/path/to/shared-dependencies.gradle" ... dependencies { ... // other dependencies } // <search> build.gradle apply from: “relative/path/to/shared-dependencies.gradle" ... dependencies { ... // other dependencies } // <core> build.gradle apply from: “relative/path/to/shared-dependencies.gradle" ... dependencies { ... // other dependencies }
  32. • Managing shared dependencies becomes easier • Eliminates repeated declaration

    of dependencies
  33. #2

  34. #2 • Fairly complex projects • Multiple modules • You

    will find a lot of repetitions in the configurations of the modules
  35. #2

  36. #2 // <login> build.gradle android { compileSdkVersion sdk.compileSdkVersion buildToolsVersion sdk.buildToolsVersion

    defaultConfig {...} buildTypes {...} }
  37. #2 // <login> build.gradle android { compileSdkVersion sdk.compileSdkVersion buildToolsVersion sdk.buildToolsVersion

    defaultConfig { minSdkVersion sdk.minSdkVersion targetSdkVersion sdk.targetSdkVersion versionCode 198828 versionName "1.5.0" testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner" consumerProguardFiles 'consumer-rules.pro' ... } buildTypes {...} }
  38. #2 // <login> build.gradle android { compileSdkVersion sdk.compileSdkVersion buildToolsVersion sdk.buildToolsVersion

    defaultConfig {...} buildTypes { debug { minifyEnabled ... proguardFiles ... } release { minifyEnabled ... proguardFiles ... } } }
  39. #2 // <login> build.gradle android { compileSdkVersion sdk.compileSdkVersion buildToolsVersion sdk.buildToolsVersion

    defaultConfig {...} buildTypes {...} }
  40. #2 // <login> build.gradle android { compileSdkVersion sdk.compileSdkVersion buildToolsVersion sdk.buildToolsVersion

    defaultConfig {...} buildTypes {...} } // <profile> build.gradle android { compileSdkVersion sdk.compileSdkVersion buildToolsVersion sdk.buildToolsVersion defaultConfig {...} buildTypes {...} }
  41. #2 // <login> build.gradle android { compileSdkVersion sdk.compileSdkVersion buildToolsVersion sdk.buildToolsVersion

    defaultConfig {...} buildTypes {...} } // <profile> build.gradle android { compileSdkVersion sdk.compileSdkVersion buildToolsVersion sdk.buildToolsVersion defaultConfig {...} buildTypes {...} } // <search> build.gradle android { compileSdkVersion sdk.compileSdkVersion buildToolsVersion sdk.buildToolsVersion defaultConfig {...} buildTypes {...} }
  42. #2 // <login> build.gradle android { compileSdkVersion sdk.compileSdkVersion buildToolsVersion sdk.buildToolsVersion

    defaultConfig {...} buildTypes {...} } // <profile> build.gradle android { compileSdkVersion sdk.compileSdkVersion buildToolsVersion sdk.buildToolsVersion defaultConfig {...} buildTypes {...} } // <search> build.gradle android { compileSdkVersion sdk.compileSdkVersion buildToolsVersion sdk.buildToolsVersion defaultConfig {...} buildTypes {...} } Problem: Repeated configuration in so many modules
  43. 1. Extract common configuration into separate file https://handstandsam.com/2019/03/12/sharing-gradle-configuration-in-multi-module-android-projects/ // common-android-config.gradle

    apply plugin: 'kotlin-android' android { compileSdkVersion sdk.compileSdkVersion defaultConfig { minSdkVersion sdk.minSdkVersion targetSdkVersion sdk.targetSdkVersion versionCode 1 versionName "1.0" testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner" } } Further reading:
  44. 1. Extract common configuration into separate file https://handstandsam.com/2019/03/12/sharing-gradle-configuration-in-multi-module-android-projects/ Further reading:

    2. Apply config to android modules // <login> build.gradle apply from: "$rootProject.projectDir/common-android-config.gradle" ...
  45. • Eliminates repeated configuration of common build logic • Same

    applies to other common configuration you may have across multiple modules. https://handstandsam.com/2019/03/12/sharing-gradle-configuration-in-multi-module-android-projects/ Further reading:
  46. Taking it even further with Kotlin DSL

  47. Why Kotlin DSL? • Kotlin is now really popular •

    Same language for code & build logic
  48. Why Kotlin DSL? • Kotlin is now really popular •

    Same language for code & build logic • Better IDE support for build scripts in Kotlin. • Jump to declaration, syntax highlighting, etc
  49. buildSrc • Gradle allows us create a module to add

    complex build related logic - like plugins, custom tasks, etc.
  50. buildSrc • Gradle allows us create a module to add

    complex build related logic - like plugins, custom tasks, etc. • It’s a regular module with it’s own: • build.gradle.kts • src/main/java or src/main/kotlin
  51. Adding dependencies versions to buildSrc Anatomy of the buildSrc module

    for dependencies versioning
  52. dependencies.gradle -> dependencies.kt // build.gradle.kts plugins { `kotlin-dsl` } repositories

    { jcenter() }
  53. dependencies.gradle -> dependencies.kt // Dependencies.kt object SdkVersions { const val

    compileSdkVersion = 28 const val minSdkVersion = 21 const val targetSdkVersion = 28 } object Deps { const val kotlinStdLib = “org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.3.41" const val gson = “com.google.code.gson:gson:2.8.5" ... object Rx { const val rxJava2 = "io.reactivex.rxjava2:rxjava:2.2.10" const val rxAndroid = "io.reactivex.rxjava2:rxandroid:2.1.1" } ... }
  54. dependencies.gradle -> dependencies.kt // Dependencies.kt object SdkVersions { const val

    compileSdkVersion = 28 const val minSdkVersion = 21 const val targetSdkVersion = 28 } object Deps { const val kotlinStdLib = “org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.3.41" const val gson = “com.google.code.gson:gson:2.8.5" ... object Rx { const val rxJava2 = "io.reactivex.rxjava2:rxjava:2.2.10" const val rxAndroid = "io.reactivex.rxjava2:rxandroid:2.1.1" } ... }
  55. dependencies.gradle -> dependencies.kt // Dependencies.kt object Deps { const val

    kotlinStdLib = “org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.3.41" const val gson = “com.google.code.gson:gson:2.8.5" } // Usage in build.gradle dependencies { implementation Deps.kotlinStdLib implementation Deps.gson ... }
  56. dependencies.gradle -> dependencies.kt // Dependencies.kt object Deps { const val

    kotlinStdLib = “org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.3.41" const val gson = “com.google.code.gson:gson:2.8.5" } // Usage in build.gradle dependencies { implementation Deps.kotlinStdLib implementation Deps.gson ... } Syntax highlighting ✅ “Jump to declaration” ✅
  57. Kotlin DSL prerequisites • Gradle 5.0 • Java 8

  58. Tips for migrating to Kotlin DSL

  59. Tips for migrating to Kotlin DSL 1. <file.gradle> becomes <file.gradle.kts>

    2. Single quotes become double quotes 3. Property assignments should have assignment operator ‘=‘ 4. Function calls should have parenthes
  60. Migrating an Android project

  61. // settings.gradle include ':app', ':data', ':domain'

  62. // settings.gradle include ':app', ':data', ':domain' // settings.gradle.kts include(":app", ":data",

    ":domain")
  63. // settings.gradle include ':app', ':data', ':domain' // settings.gradle.kts include(":app", ":data",

    ":domain") ’:app’ becomes “:app” include becomes include()
  64. // app-level build.gradle

  65. // app-level build.gradle apply plugin: 'com.android.application' apply plugin: 'kotlin-android' android

    { compileSdkVersion 28 defaultConfig { applicationId "com.segunfamisa.kotlindsl" minSdkVersion 21 targetSdkVersion 28 versionCode 1 versionName "1.0" } buildTypes { release { minifyEnabled true proguardFiles ... } } } dependencies { implementation fileTree(dir: 'libs', include: ['*.jar']) implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.3.31" implementation "androidx.appcompat:appcompat:1.0.2" }
  66. // app-level build.gradle.kts apply(plugin = "com.android.application") apply(plugin = "kotlin-android") android

    { compileSdkVersion(28) defaultConfig { applicationId "com.segunfamisa.kotlindsl" minSdkVersion(21) targetSdkVersion(28) versionCode = 1 versionName = "1.0" } buildTypes { getByName("release") { isMinifyEnabled = true proguardFiles(getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro') } } } dependencies { implementation(fileTree(mapOf("dir" to "libs", "include" to listOf("*.jar")))) implementation("org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.3.31") implementation("androidx.appcompat:appcompat:1.0.2") }
  67. What changed? apply plugin: 'com.android.application' apply plugin: 'kotlin-android' android {

    compileSdkVersion 28 defaultConfig { applicationId "com.segunfamisa.kotlindsl" minSdkVersion 21 targetSdkVersion 28 versionCode 1 versionName "1.0" } buildTypes { release { minifyEnabled true proguardFiles ... } } } dependencies { implementation fileTree(dir: 'libs', include: ['*.jar']) implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.3.31" implementation "androidx.appcompat:appcompat:1.0.2" }
  68. What changed? apply(plugin = "com.android.application") apply(plugin = "kotlin-android") android {

    compileSdkVersion 28 defaultConfig { applicationId "com.segunfamisa.kotlindsl" minSdkVersion 21 targetSdkVersion 28 versionCode 1 versionName "1.0" } buildTypes { release { minifyEnabled true proguardFiles ... } } } dependencies { implementation fileTree(dir: 'libs', include: ['*.jar']) implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.3.31" implementation "androidx.appcompat:appcompat:1.0.2" }
  69. What changed? apply(plugin = "com.android.application") apply(plugin = "kotlin-android") android {

    compileSdkVersion 28 defaultConfig { applicationId "com.segunfamisa.kotlindsl" minSdkVersion 21 targetSdkVersion 28 versionCode 1 versionName "1.0" } buildTypes { release { minifyEnabled true proguardFiles ... } } } dependencies { implementation fileTree(dir: 'libs', include: ['*.jar']) implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.3.31" implementation "androidx.appcompat:appcompat:1.0.2" }
  70. What changed? apply(plugin = "com.android.application") apply(plugin = "kotlin-android") android {

    compileSdkVersion(28) defaultConfig { applicationId "com.segunfamisa.kotlindsl" minSdkVersion(21) targetSdkVersion(28) versionCode 1 versionName "1.0" } buildTypes { release { minifyEnabled true proguardFiles ... } } } dependencies { implementation fileTree(dir: 'libs', include: ['*.jar']) implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.3.31" implementation "androidx.appcompat:appcompat:1.0.2" }
  71. What changed? apply(plugin = "com.android.application") apply(plugin = "kotlin-android") android {

    compileSdkVersion(28) defaultConfig { applicationId "com.segunfamisa.kotlindsl" minSdkVersion(21) targetSdkVersion(28) versionCode 1 versionName "1.0" } buildTypes { release { minifyEnabled true proguardFiles ... } } } dependencies { implementation fileTree(dir: 'libs', include: ['*.jar']) implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.3.31" implementation "androidx.appcompat:appcompat:1.0.2" }
  72. What changed? apply(plugin = "com.android.application") apply(plugin = "kotlin-android") android {

    compileSdkVersion(28) defaultConfig { applicationId "com.segunfamisa.kotlindsl" minSdkVersion(21) targetSdkVersion(28) versionCode 1 versionName "1.0" } buildTypes { getByName("release") { isMinifyEnabled = true proguardFiles(getDefaultProguardFile(‘...’), 'proguard-rules.pro') } } } dependencies { implementation fileTree(dir: 'libs', include: ['*.jar']) implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.3.31" implementation "androidx.appcompat:appcompat:1.0.2" }
  73. What changed? apply(plugin = "com.android.application") apply(plugin = "kotlin-android") android {

    compileSdkVersion(28) defaultConfig { applicationId "com.segunfamisa.kotlindsl" minSdkVersion(21) targetSdkVersion(28) versionCode 1 versionName "1.0" } buildTypes { getByName("release") { isMinifyEnabled = true proguardFiles(getDefaultProguardFile(‘...’), 'proguard-rules.pro') } } } dependencies { implementation fileTree(dir: 'libs', include: ['*.jar']) implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.3.31" implementation "androidx.appcompat:appcompat:1.0.2" }
  74. What changed? apply(plugin = "com.android.application") apply(plugin = "kotlin-android") android {

    compileSdkVersion(28) defaultConfig { applicationId "com.segunfamisa.kotlindsl" minSdkVersion(21) targetSdkVersion(28) versionCode 1 versionName "1.0" } buildTypes { getByName("release") { isMinifyEnabled = true proguardFiles(getDefaultProguardFile(‘...’), 'proguard-rules.pro') } } } dependencies { implementation(fileTree(mapOf("dir" to "libs", "include" to listOf("*.jar")))) implementation("org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.3.31") implementation("androidx.appcompat:appcompat:1.0.2") }
  75. // app-level build.gradle.kts apply(plugin = "com.android.application") apply(plugin = "kotlin-android") android

    { compileSdkVersion(28) defaultConfig { applicationId "com.segunfamisa.kotlindsl" minSdkVersion(21) targetSdkVersion(28) versionCode = 1 versionName = "1.0" } buildTypes { getByName("release") { isMinifyEnabled = true proguardFiles(getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro') } } } dependencies { implementation(fileTree(mapOf("dir" to "libs", "include" to listOf("*.jar")))) implementation("org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.3.31") implementation("androidx.appcompat:appcompat:1.0.2") }
  76. // top-level build.gradle

  77. // top-level build.gradle buildscript { ext.kotlin_version = '1.3.31' repositories {

    google() jcenter() } dependencies { classpath 'com.android.tools.build:gradle:3.4.1' classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version" } } allprojects { repositories { google() jcenter() } }
  78. // top-level build.gradle.kts buildscript { extra.apply { set("kotlin_version", "1.3.31") }

    repositories { google() jcenter() } dependencies { classpath("com.android.tools.build:gradle:3.4.1") classpath("org.jetbrains.kotlin:kotlin-gradle-plugin:${extras.get("kotlin_version")}) } } allprojects { repositories { google() jcenter() } }
  79. What changed?

  80. // top-level build.gradle buildscript { ext.kotlin_version = '1.3.31' repositories {

    google() jcenter() } dependencies { classpath 'com.android.tools.build:gradle:3.4.1' classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version" } } allprojects { repositories { google() jcenter() } } What changed?
  81. What changed? // top-level build.gradle.kts buildscript { extra.apply { set("kotlin_version",

    "1.3.31") } repositories { google() jcenter() } dependencies { classpath("com.android.tools.build:gradle:3.4.1") classpath("org.jetbrains.kotlin:kotlin-gradle-plugin:${extras.get("kotlin_version")}) } } allprojects { repositories { google() jcenter() } }
  82. // top-level build.gradle buildscript { extra.apply { set("kotlin_version", "1.3.31") }

    repositories { google() jcenter() } dependencies { classpath 'com.android.tools.build:gradle:3.4.1' classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version" } } allprojects { repositories { google() jcenter() } } What changed?
  83. // top-level build.gradle.kts buildscript { extra.apply { set("kotlin_version", "1.3.31") }

    repositories { google() jcenter() } dependencies { classpath("com.android.tools.build:gradle:3.4.1") classpath("org.jetbrains.kotlin:kotlin-gradle-plugin:${extras.get("kotlin_version")}) } } allprojects { repositories { google() jcenter() } } What changed?
  84. // top-level build.gradle.kts buildscript { extra.apply { set("kotlin_version", "1.3.31") }

    repositories { google() jcenter() } dependencies { classpath("com.android.tools.build:gradle:3.4.1") classpath("org.jetbrains.kotlin:kotlin-gradle-plugin:${extras.get("kotlin_version")}) } } allprojects { repositories { google() jcenter() } }
  85. Custom Gradle Plugin

  86. Custom Gradle Plugin • We could use a custom plugin

    to apply common configuration across multiple modules
  87. class AwesomePlugin : Plugin<Project> { override fun apply(project: Project) {

    ... } }
  88. class AwesomePlugin : Plugin<Project> { override fun apply(project: Project) {

    with(project) { project.plugins.all { when (this) { is AppPlugin, is LibraryPlugin -> extensions.getByType<TestedExtension>().apply { configureAndroidModule(extension = this, project = project) } } } } } }
  89. class AwesomePlugin : Plugin<Project> { override fun apply(project: Project) {

    with(project) { project.plugins.all { when (this) { is AppPlugin, is LibraryPlugin -> extensions.getByType<TestedExtension>().apply { configureAndroidModule(extension = this, project = project) } } } } } }
  90. class AwesomePlugin : Plugin<Project> { override fun apply(project: Project) {

    with(project) { project.plugins.all { when (this) { is AppPlugin, is LibraryPlugin -> extensions.getByType<TestedExtension>().apply { configureAndroidModule(extension = this, project = project) } } } } } }
  91. private fun TestedExtension.configureAndroidModule(project: Project) { }

  92. private fun TestedExtension.configureAndroidModule(project: Project) { setCompileSdkVersion(28) defaultConfig.apply { minSdkVersion(21) targetSdkVersion(28)

    compileOptions { sourceCompatibility = JavaVersion.VERSION_1_8 targetCompatibility = JavaVersion.VERSION_1_8 } } ... }
  93. Apply new plugin to all modules plugins { id("com.android.application") kotlin("android")

    kotlin("android.extensions") } apply { from("${rootProject.projectDir}/shared-dependencies.gradle") } apply<AwesomePlugin>() ...
  94. Current pain points with Kotlin DSL

  95. Current pain points with Kotlin DSL • IDE support is

    not yet at
  96. Current pain points with Kotlin DSL • IDE support is

    not yet at • Additional configuration time in your build process
  97. Current pain points with Kotlin DSL • IDE support is

    not yet at • Additional configuration time in your build process • Applying config from an external gradle.kts file doesn’t quite work: • You either have to leave as .gradle files or follow another work-around (see: https://github.com/gradle/kotlin-dsl/issues/1287)
  98. Current pain points with Kotlin DSL • IDE support is

    not yet at • Additional configuration time in your build process • Applying config from an external gradle.kts file doesn’t quite work: • You either have to leave as .gradle files or follow another work-around (see: https://github.com/gradle/kotlin-dsl/issues/1287) • Weird, but sometimes, some things in the plugin show a compiler warning, but it actually works
  99. Final words

  100. Final words • Keep it DRY (Don’t Repeat Yourself) -

    rule of three applies here
  101. Final words • Keep it DRY (Don’t Repeat Yourself) -

    rule of three applies here • Modular code rocks
  102. Final words • Keep it DRY (Don’t Repeat Yourself) -

    rule of three applies here • Modular code rocks • Take advantage of IDE support with Kotlin DSL
  103. Resources https://handstandsam.com/2019/03/12/sharing-gradle-configuration-in-multi-module-android-projects/ https://segunfamisa.com/posts/android-gradle-extra-properties https://gradle.com/blog/getting-started-with-gradle-kotlin-dsl/ https://github.com/gradle/kotlin-dsl Build Bigger, Better: Gradle for

    Large Projects (Google I/O'19)
  104. Thanks! Segun Famisa, Android GDE