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@segunfamisa 

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 

Improving your gradle experience 

#0 

Small project, single or few modules #0 

// 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 

// build.gradle apply plugin: 'kotlin' ... dependencies { ... implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.3.31" implementation "io.reactivex.rxjava2:rxjava:2.2.5" } // 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 

// 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" } // 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 

#0 // 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" } // 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 

#0 - solution 

#0 - solution Solving the duplication problem with Gradle extra (ext) properties feature 

// dependencies.gradle ext { ... libraries = [ rxJavaVersion : '2.2.5' rxAndroidVersion : '2.1.0' kotlinVersion : '1.3.31' ] } 1. Externalize dependencies 

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

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

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

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

• Managing/updating versions of dependencies is now easier - just need to change in one place • Still has the problem of duplication of dependencies 

#1 

#1 • Fairly complex projects • Multiple modules • You will find a lot of repetitions in the dependencies 

#1 // 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 } 

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

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

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

#1 // 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:$libs.jUnitVersion" ... // other dependencies } // build.gradle dependencies { implementation fileTree(dir: 'libs', include: ['*.jar']) implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version" implementation "io.reactivex.rxjava2:rxjava:$rxJavaVersion" testImplementation "junit:junit:$libs.jUnitVersion" ... // other dependencies } // 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:$libs.jUnitVersion" ... // other dependencies } // build.gradle dependencies { implementation fileTree(dir: 'libs', include: ['*.jar']) implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version" implementation "io.reactivex.rxjava2:rxjava:$rxJavaVersion" testImplementation "junit:junit:$libs.jUnitVersion" ... // other dependencies } Problem: Repeated declarations of dependencies in so many modules 

#1 Solution: extract common/shared dependencies and apply to the modules 

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' } 

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

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

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

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

• Managing shared dependencies becomes easier • Eliminates repeated declaration of dependencies 

#2 

#2 • Fairly complex projects • Multiple modules • You will find a lot of repetitions in the configurations of the modules 

#2 

#2 // build.gradle android { compileSdkVersion sdk.compileSdkVersion buildToolsVersion sdk.buildToolsVersion defaultConfig {...} buildTypes {...} } 

#2 // 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 {...} } 

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

#2 // build.gradle android { compileSdkVersion sdk.compileSdkVersion buildToolsVersion sdk.buildToolsVersion defaultConfig {...} buildTypes {...} } 

#2 // build.gradle android { compileSdkVersion sdk.compileSdkVersion buildToolsVersion sdk.buildToolsVersion defaultConfig {...} buildTypes {...} } // build.gradle android { compileSdkVersion sdk.compileSdkVersion buildToolsVersion sdk.buildToolsVersion defaultConfig {...} buildTypes {...} } 

#2 // build.gradle android { compileSdkVersion sdk.compileSdkVersion buildToolsVersion sdk.buildToolsVersion defaultConfig {...} buildTypes {...} } // build.gradle android { compileSdkVersion sdk.compileSdkVersion buildToolsVersion sdk.buildToolsVersion defaultConfig {...} buildTypes {...} } // build.gradle android { compileSdkVersion sdk.compileSdkVersion buildToolsVersion sdk.buildToolsVersion defaultConfig {...} buildTypes {...} } 

#2 // build.gradle android { compileSdkVersion sdk.compileSdkVersion buildToolsVersion sdk.buildToolsVersion defaultConfig {...} buildTypes {...} } // build.gradle android { compileSdkVersion sdk.compileSdkVersion buildToolsVersion sdk.buildToolsVersion defaultConfig {...} buildTypes {...} } // build.gradle android { compileSdkVersion sdk.compileSdkVersion buildToolsVersion sdk.buildToolsVersion defaultConfig {...} buildTypes {...} } Problem: Repeated configuration in so many modules 

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: 

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 // build.gradle apply from: "$rootProject.projectDir/common-android-config.gradle" ... 

• 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: 

Taking it even further with Kotlin DSL 

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

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 

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

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 

Adding dependencies versions to buildSrc Anatomy of the buildSrc module for dependencies versioning 

dependencies.gradle -> dependencies.kt // build.gradle.kts plugins { `kotlin-dsl` } repositories { jcenter() } 

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" } ... } 

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" } ... } 

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 ... } 

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” ✅ 

Kotlin DSL prerequisites • Gradle 5.0 • Java 8 

Tips for migrating to Kotlin DSL 

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 

Migrating an Android project 

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

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

// settings.gradle include ':app', ':data', ':domain' // settings.gradle.kts include(":app", ":data", ":domain") ’:app’ becomes “:app” include becomes include() 

// app-level build.gradle 

// 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" } 

// 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") } 

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" } 

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" } 

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" } 

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" } 

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" } 

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" } 

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" } 

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") } 

// 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") } 

// top-level build.gradle 

// 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() } } 

// 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? 

// 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? 

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() } } 

// 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? 

// 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? 

// 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() } } 

Custom Gradle Plugin 

Custom Gradle Plugin • We could use a custom plugin to apply common configuration across multiple modules 

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

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

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

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

private fun TestedExtension.configureAndroidModule(project: Project) { } 

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 } } ... } 

Apply new plugin to all modules plugins { id("com.android.application") kotlin("android") kotlin("android.extensions") } apply { from("${rootProject.projectDir}/shared-dependencies.gradle") } apply() ... 

Current pain points with Kotlin DSL 

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

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

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) 

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 

Final words 

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

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

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 

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) 

Thanks! Segun Famisa, Android GDE