Playing nice with Gradle - droidcon KE

Presentation given at droidcon KE, Nairobi, 2019

Abstract:
Gradle is the most popular build system in use today for building Android projects. It is an amazing tool that has improved how we build projects especially when we compare to the previous build systems used for Android development.

As your project starts to scale, so does the Gradle setup start to get complicated - from build performance, to configuring plugins, to managing dependencies, to managing multiple modules. Gradle by default makes use of Groovy language, which often does not provide the full features of static typing - hence making it more difficult to customize.

If like me, you’re in a love-hate relationship with Gradle, then, this talk is for you.

In this talk, we will go through top tips to make Gradle work for us as Android developers.

We will talk about different quick wins to make maintaining our Gradle configuration easy by:
avoiding repetitive code as your project modules continue to grow, and
writing your build configuration partly or fully in Kotlin, hence taking advantage of the Kotlin DSL feature.
You will leave this talk with a lot of ideas of how to improve the Gradle setup of your project.

Most of these ideas will be something you can immediately implement while some may require a little more effort. Ultimately we will be able to make Gradle work for you to achieve the best results.

Resource links in the slides:
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
https://blog.codinghorror.com/rule-of-three/

Transcript

1. Playing nice with Gradle
   the elephant in the room
   Segun Famisa, Android GDE
   droidcon KE
   August, 2019
   

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2. @segunfamisa
   

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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
   • Resources
   

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4. Improving your gradle
   experience
   

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5. #0
   

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6. Small project, single or few modules
   #0
   

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7. // 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
   

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8. // 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
   

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9. // 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
   

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10. #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
    

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11. #0 - solution
    

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12. #0 - solution
    Solving the duplication problem with Gradle extra (ext) properties feature
    

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

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

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15. 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"
    }
    

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16. 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"
    }
    

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17. 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"
    }
    

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

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19. #1
    

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20. #1
    • Fairly complex projects
    • Multiple modules
    • You will find a lot of repetitions in the
    dependencies
    

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21. #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
    }
    

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22. #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
    }
    

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23. #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
    }
    

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24. #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
    }
    

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25. #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
    

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26. #1
    Solution: extract common/shared dependencies and apply to the modules
    

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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'
    }
    

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

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29. 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
    }
    

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30. 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
    }
    

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31. 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
    }
    

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

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33. #2
    

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34. #2
    • Fairly complex projects
    • Multiple modules
    • You will find a lot of repetitions in the
    configurations of the modules
    

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35. #2
    

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36. #2
    // build.gradle
    android {
    compileSdkVersion sdk.compileSdkVersion
    buildToolsVersion sdk.buildToolsVersion
    defaultConfig {...}
    buildTypes {...}
    }
    

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37. #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 {...}
    }
    

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38. #2
    // build.gradle
    android {
    compileSdkVersion sdk.compileSdkVersion
    buildToolsVersion sdk.buildToolsVersion
    defaultConfig {...}
    buildTypes {
    debug {
    minifyEnabled ...
    proguardFiles ...
    }
    release {
    minifyEnabled ...
    proguardFiles ...
    }
    }
    }
    

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39. #2
    // build.gradle
    android {
    compileSdkVersion sdk.compileSdkVersion
    buildToolsVersion sdk.buildToolsVersion
    defaultConfig {...}
    buildTypes {...}
    }
    

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

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41. #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 {...}
    }
    

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42. #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
    

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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:
    

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

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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:
    

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46. Taking it even further with Kotlin
    DSL
    

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

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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
    

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49. Kotlin DSL prerequisites
    • Gradle 5.0
    • Java 8
    

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50. Tips for migrating to Kotlin DSL
    

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51. Tips for migrating to Kotlin DSL
    1. becomes
    2. Single quotes become double quotes
    3. Property assignments should have assignment operator ‘=‘
    4. Function calls should have parenthes
    

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

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53. 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
    

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

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

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56. 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"
    }
    ...
    }
    

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57. 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"
    }
    ...
    }
    

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58. 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
    ...
    }
    

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59. 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” ✅
    

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60. Migrating an Android project
    

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

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

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

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64. // app-level build.gradle
    

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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"
    }
    

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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")
    }
    

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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"
    }
    

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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"
    }
    

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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"
    }
    

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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"
    }
    

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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"
    }
    

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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"
    }
    

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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"
    }
    

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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")
    }
    

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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")
    }
    

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76. // top-level build.gradle
    

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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()
    }
    }
    

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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()
    }
    }
    

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79. What changed?
    

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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?
    

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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()
    }
    }
    

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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?
    

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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?
    

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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()
    }
    }
    

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85. Current pain points with Kotlin DSL
    

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

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

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88. Final words
    

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

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

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91. 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
    

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92. 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
    https://blog.codinghorror.com/rule-of-three/
    

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93. Thanks!
    Segun Famisa, Android GDE
    

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