Deep Dive into the Android Gradle Plugin (Droidcon UK 2018)

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Deep Dive into the Android Gradle Plugin John Rodriguez

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Build phases

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• Initialization • Conﬁguration • Execution Build phases rootProject.name = 'cash' include ':analytics' include ':app' include ':db' include ':keypad' include ':presenters' include ':protos' include ':screens' include ':viewmodels'

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• Initialization • Conﬁguration • Execution Build phases Settings rootProject.name = 'cash' include ':analytics' include ':app' include ':db' include ':keypad' include ':presenters' include ':protos' include ':screens' include ':viewmodels' project project project project project project project project project

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• Initialization • Configuration • Execution Build phases project('cash') project(':analytics') project(':db') project(':app') project(':keypad') project(':presenters') project(':protos') project(':screens') project(':viewmodels') > Configure project : > Configure project :analytics > Configure project :app > Configure project :db > Configure project :keypad > Configure project :presenters > Configure project :protos > Configure project :screens > Configure project :viewmodels

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• Initialization • Configuration • Execution Build phases project('cash') project(':analytics') project(':db') project(':app') project(':keypad') project(':presenters') project(':protos') project(':screens') project(':viewmodels') > Configure project : > Configure project :db > Configure project :protos ./gradlew :db:assembleDebug —configure-on-demand

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Conﬁguration buildscript { repositories { google() jcenter() }d dependencies { classpath 'com.android.tools.build:gradle:3.2.1' }f }e

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Conﬁguration buildscript { repositories { google() jcenter() }d dependencies { classpath 'com.android.tools.build:gradle:3.2.1' classpath 'org.jetbrains.kotlin:kotlin-gradle-plugin:1.2.71' classpath 'net.ltgt.gradle:gradle-errorprone-plugin:0.0.16' classpath 'com.squareup.sqldelight:android-gradle-plugin:1.0.0' }f }e

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Conﬁguration apply plugin: 'com.android.application' apply plugin: 'com.android.library'

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class GreetingPlugin implements Plugin { @Override void apply(Project project) { }f }e

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class GreetingPlugin implements Plugin { @Override void apply(Project project) { project.tasks.register('Greeting') { it.doLast { println 'Hello from the Greeting Plugin' }b }a }f }e

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class GreetingPlugin implements Plugin { @Override void apply(Project project) { project.tasks.register('Greeting') { it.doLast { println 'Hello from the Greeting Plugin' }b }a }f }e project.apply plugin: GreetingPlugin

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class GreetingPluginExtension { String message String greeter }a class GreetingPlugin implements Plugin { @Override void apply(Project project) { project.tasks.register('Greeting') { it.doLast { println 'Hello from the Greeting Plugin' }b }a }f }e apply plugin: GreetingPlugin

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class GreetingPluginExtension {1 String message String greeter }a class GreetingPlugin implements Plugin {2 @Override void apply(Project project) {3 def extension = project.extensions.create('greeting', GreetingPluginExtension) project.tasks.register('Greeting') {4 it.doLast {0 println 'Hello from the Greeting Plugin' }b }a }f }e apply plugin: GreetingPlugin

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class GreetingPluginExtension {1 String message String greeter }a class GreetingPlugin implements Plugin {2 @Override void apply(Project project) {3 def extension = project.extensions.create('greeting', GreetingPluginExtension) project.tasks.register('Greeting') {4 it.doLast {0 println "${extension.message} from ${extension.greeter}" }b }a }f }e apply plugin: GreetingPlugin

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apply plugin: GreetingPlugin greeting { message 'Hi' greeter 'Gradle' } $ ./gradlew Greeting > Task :Greeting Hi from Gradle

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interface Project extends ExtensionAware, PluginAware { } interface ExtensionAware { ExtensionContainer getExtensions(); } interface PluginAware { void apply(…); PluginManager getPluginManager(); }

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class SomeTask extends DefaultTask { @OutputDirectory File getOutputDir() {…} @InputFiles List getInputFiles() {…} @TaskAction void doStuff() {…}

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• Initialization • Conﬁguration • Execution Build phases

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• Initialization • Conﬁguration • Execution Build phases ./gradlew :db:assembleDebug

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Notiﬁcations project.tasks.whenTaskAdded {} project.beforeEvaluate {} project.afterEvaluate {} gradle.projectsEvaluated {} gradle.taskGraph.whenReady {} gradle.taskGraph.beforeTask {} gradle.taskGraph.afterTask {}

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Debugging Builds

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$ ./gradlew task

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$ ./gradlew -Dorg.gradle.debug=true task

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$ ./gradlew --no-daemon --no-build-cache —rerun-tasks / -Dorg.gradle.debug=true task

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$ ./gradlew --no-daemon --no-build-cache —rerun-tasks / -Dorg.gradle.debug=true task To honour the JVM settings for this build a new JVM will be forked. Please consider using the daemon: https://docs.gradle.org/4.10.2/ userguide/gradle_daemon.html. > Starting Daemon

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dependencies { compileOnly ‘com.android.tools.build:gradle:3.2.1' }

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gradle.taskGraph.whenReady { def dot = new File(rootProject.buildDir, 'project.dot') gradle.taskGraph.allTasks.each { task -> task.taskDependencies.getDependencies(task).each { dep -> // add task -> dep to graph }a }b 'dot -Tpng -O project.dot'.execute(…) }c

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gradle.taskGraph.whenReady { def dot = new File(rootProject.buildDir, 'project.dot') def startTasks = gradle.startParameter.getTaskNames().join(" ") println "command: ./gradlew " + startTasks gradle.taskGraph.allTasks.each { task -> println "task: " + task.name + ", class: " + task.class.name task.taskDependencies.getDependencies(task).each {…}a }b 'dot -Tpng -O project.dot'.execute(…) }c

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command: ./gradlew app:assembleDebug compileJava -> JavaCompile processResources -> ProcessResources classes -> DefaultTask jar -> Jar checkDebugClasspath -> AppClasspathCheckTask preBuild -> DefaultTask preDebugBuild -> AppPreBuildTask compileDebugAidl -> AidlCompile compileDebugRenderscript -> RenderscriptCompile checkDebugManifest -> CheckManifest generateDebugBuildConfig -> GenerateBuildConfig prepareLintJar -> PrepareLintJar mainApkListPersistenceDebug -> MainApkListPersistence generateDebugResValues -> GenerateResValues generateDebugResources -> DefaultTask mergeDebugResources -> MergeResources …e

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gradle.taskGraph.whenReady { def dot = new File(rootProject.buildDir, 'project.dot') def startTasks = gradle.startParameter.getTaskNames().join(" ") println "command: ./gradlew " + startTasks gradle.taskGraph.allTasks.each { task -> println "task: " + task.name + ", class: " + task.class.name println " inputs: " task.inputs.each { it.files.each { println " " + it } } println " outputs: " task.outputs.each { it.files.each { println " " + it } } task.taskDependencies.getDependencies(task).each {…}a }b 'dot -Tpng -O project.dot'.execute(…) }c

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gradle.taskGraph

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gradle.taskGraph.afterTask { task -> println " inputs: " task.inputs.files.each { println " " + it } println " outputs: " task.outputs.files.each { println " " + it } }

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> Task :app:checkDebugClasspath inputs: …/gradle-3.2.1.jar …/builder-3.2.1.jar …/tracker-26.2.1.jar …/shared-26.2.1.jar …/crash-26.2.1.jar … outputs: …/app/build/intermediates/checkDebugClasspath/debug

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buildTypes { debug { applicationIdSuffix '.debug' minifyEnabled false proguardFile file('proguard-cash.pro') proguardFile file('proguard-cash-debug.pro') } release { minifyEnabled true shrinkResources true proguardFile file('proguard-cash.pro') } }

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productFlavors { flavorDimensions 'environment' internal { dimension 'environment' applicationId 'com.squareup.cash.beta' } production { dimension 'environment' applicationId 'com.squareup.cash' } } debug release

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production internal release debug

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production internal release debug internal Release

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production internal release debug internal Release Release

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production internal release debug internalDebug internalRelease productionDebug productionRelease release

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Configurations

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dependencies { implementation project(‘:api') api project(‘:db’) }a

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dependencies { implementation project(‘:api') api project(‘:db’) kapt project(‘:dagger’) testImplementation deps.mockito }a

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Images from https://jeroenmols.com/blog/2017/06/14/androidstudio3/

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Images from https://jeroenmols.com/blog/2017/06/14/androidstudio3/

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Images from https://jeroenmols.com/blog/2017/06/14/androidstudio3/

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:app dependencies { implementation project(':api') }a

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:app dependencies { implementation project(':api') }a :api dependencies { implementation project(':protos') implementation deps.retrofit implementation deps.rx2 }

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:app dependencies { implementation project(':api') } :api dependencies { implementation project(':protos') implementation deps.retrofit implementation deps.rx2 }

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:app dependencies { implementation project(':api') }a :api dependencies { implementation project(':protos') implementation deps.retrofit implementation deps.rx2 }a

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:app dependencies { implementation project(':api') } :api dependencies { implementation project(':protos') implementation deps.retrofit implementation deps.rx2 } :protos dependencies { api deps.wire.runtime }

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:app dependencies { implementation project(':api') } :api dependencies { api project(':protos') implementation deps.retrofit implementation deps.rx2 } :protos dependencies { api deps.wire.runtime }

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:app dependencies { implementation project(':api') } :api dependencies { api project(':protos') implementation deps.retrofit implementation deps.rx2 } :protos dependencies { api deps.wire.runtime }

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:app dependencies { implementation project(':api') }a :api dependencies { api project(':protos') implementation deps.retrofit api deps.rx2 }b :protos dependencies { api deps.wire.runtime }c

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:app dependencies { implementation project(':api') } :api dependencies { api project(':protos') api deps.retrofit api deps.rx2 } :protos dependencies { api deps.wire.runtime }

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class AppClasspathCheckTask extends ClasspathComparisionTask { @TaskAction void run() { compareClasspaths(); } }e

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class AppClasspathCheckTask extends ClasspathComparisionTask { @Override void onDifferentVersionsFound(…)a{ String message = String.format( "Conflict with dependency '%1$s:%2$s' in project '%3$s'. Resolved versions for runtime classpath (%4$s) and compile classpath (%5$s) differ. This can lead to runtime crashes. To resolve this issue …\n”, …); reporter.reportWarning(EvalIssueReporter.Type.GENERIC, message); } @TaskAction void run() { compareClasspaths(); } }e

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class AppClasspathCheckTask extends ClasspathComparisionTask { a{…} }e

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class AppClasspathCheckTask extends ClasspathComparisionTask { a{…} static class ConfigAction TaskConfigAction { String getName() { return variantScope.getTaskName("check", "Classpath"); } @Override void execute(@NonNull AppClasspathCheckTask task) { task.setVariantName(variantScope.getFullVariantName()); task.runtimeClasspath = variantScope.getArtifactCollection(RUNTIME_CLASSPATH, …); task.compileClasspath = variantScope.getArtifactCollection(COMPILE_CLASSPATH, …); } } }e

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:moduleA dependencies { api libs.retrofit implementation libs.okhttp } :moduleB dependencies { implementation libs.retrofit } :app dependencies { implementation project(':module-a') implementation project(':module-b') }

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$ ./gradlew app:dependencies debugCompileClasspath: debug +--- project :module-a | \--- com.squareup.retrofit2:retrofit:2.3.0 | \--- com.squareup.okhttp3:okhttp:3.8.0 | \--- com.squareup.okio:okio:1.13.0 \--- project :module-b … debugRuntimeClasspath: debug +--- project :module-a | +--- com.squareup.retrofit2:retrofit:2.3.0 | | \--- com.squareup.okhttp3:okhttp:3.8.0 -> 3.9.0 | | \--- com.squareup.okio:okio:1.13.0 | \--- com.squareup.okhttp3:okhttp:3.9.0 (*) \--- project :module-b \--- com.squareup.retrofit2:retrofit:2.3.0 (*)

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class JavaPreCompileTask extends AndroidBuilderTask { @OutputFile File getProcessorListFile() { return processorListFile; } @TaskAction void preCompile() { Set classNames = Sets.newHashSet(); classNames.addAll( convertArtifactsToNames( collectAnnotationProcessors(annotationProcessorConfiguration) )); Gson gson = new GsonBuilder().create(); try (FileWriter writer = new FileWriter(processorListFile)) { gson.toJson(classNames, writer); } } /** * Returns a List of packages in the configuration believed to

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} } /** * Returns a List of packages in the configuration believed to * contain an annotation processor. * * We assume a package has an annotation processor if it contains the * META-INF/services/javax.annotation.processing.Processor file. */ List<…> collectAnnotationProcessors(ArtifactCollection config) {}

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> Task :app:mergeDebugResources inputs: ~/.gradle/caches/…/aapt2-3.2.1-4818971-osx.jar/… …/app/build/generated/res/resValues/debug …/app/build/generated/res/rs/debug …/app/src/main/res …/app/src/debug/res outputs: …/app/build/intermediates/blame/res/debug …/app/build/generated/res/pngs/debug …/app/build/intermediates/incremental/mergeDebugResources …/app/build/intermediates/res/merged/debug

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> Task :app:processDebugResources inputs: ~/.gradle/caches/…/aapt2-3.2.1-4818971-osx.jar/… …/app/build/intermediates/apk_list/…/apk-list.gson …/app/build/intermediates/res/merged/debug …/app/build/intermediates/split_list/…/split-list.gson …/app/build/intermediates/merged_manifests/…/merged outputs: …/app/build/intermediates/incremental/processDebugResources …/app/build/intermediates/processed_res/…/out …/app/build/generated/not_namespaced_r_class_sources/…/r …/app/build/intermediates/res/symbol-table…/…/package-aware-r.txt …/app/build/intermediates/symbols/debug/R.txt

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Resource processing • Before in aapt: take all resources and outputs one binary • Now in aapt2: compile + link • converts individual resources into binary ﬂat ﬁles • merge at the end • uses Gradle incremental check feature for compile avoidance • Improving mergeReleaseResources for libraries • avoids full merge of resources for all the transitive dependencies

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ArtifactTransform API Request • aar -> android-manifest Internally • aar -> exploded-aar • exploded-aar -> android-manifest • Runs once, cached globally • Downloaded, transformed on demand

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android.libraryVariants.all { variant -> def runtimeConfiguration = variant.getRuntimeConfiguration() runtimeConfiguration.getIncoming() .artifactView(new Action() { void execute(ArtifactView.ViewConfiguration config2) { config2.attributes(new Action() { void execute(AttributeContainer c) { c.attribute(Attribute.of("artifactType", String), “android-assets“) } }) } }) .artifacts.artifacts.each { result -> // This file is an asset def file = result.file }

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ArtifactTransform API “give me all the assets” Before: view = configuration.getFiles() // check if AAR (could have JARS), then find assets… After: view = configuration.getIncoming().artifactView(config -> {...}) Downstream tasks can set up their inputs as a lazy FileCollection • allowing resolution on demand during task execution, as opposed to configuration. FileCollection will only contain the assets and tasks generating them • helpful for variant-awareness by not generating extra tasks

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• the process of transforming .class bytecode into .dex bytecode for Android  • D8 - new dex compiler, replaces DX  • DX takes a class,zip,jar,apk and converts to a single dex  • When comparing with the current DX compiler, D8 compiles faster and outputs smaller .dex ﬁles, while having the same or better app runtime performance.  • To test in 3.0, android.enableD8=true  • Set to default in 3.1.  Dexing

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DX $ $ANDROID_HOME/build-tools/LATEST/dx --dex —output=out input.jar D8 Debug mode build: $ java -jar build/libs/d8.jar --output out input.jar Release mode build: $ java -jar build/libs/d8.jar --release --output out input.jar Dexing

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• Migration from PSI to UAST as of AGP 3.0 • Jetbrains + Google • Kotlin UAST support as of AGP 3.1 • Quick ﬁxes • Lots more detail here: • Lint to the Finish Line: https://www.youtube.com/watch?v=wFe0WZm_xm8 • Kotlin Static Analysis with Android Lint: https://www.youtube.com/watch?v=p8yX5-lPS6o Lint

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Improving your Builds

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enum class BooleanOption( override val propertyName: String, override val defaultValue: Boolean = false, override val status: Option.Status = Option.Status.EXPERIMENTAL, override val additionalInfo: String = "" ) : Option { ENABLE_AAPT2("android.enableAapt2", true, DeprecationReporter.DeprecationTarget.AAPT), ENABLE_BUILD_CACHE("android.enableBuildCache", true), ENABLE_PROFILE_JSON("android.enableProfileJson", false), // Used by Studio as workaround for b/71054106, b/75955471 ENABLE_SDK_DOWNLOAD("android.builder.sdkDownload", true, status = Option.Status.STABLE), ENABLE_TEST_SHARDING("android.androidTest.shardBetweenDevices"), ENABLE_DEX_ARCHIVE( "android.useDexArchive", true, aDeprecationReporter.DeprecationTarget.LEGACY_DEXER ),a

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VERSION_CHECK_OVERRIDE_PROPERTY("android.overrideVersionCheck"), OVERRIDE_PATH_CHECK_PROPERTY("android.overridePathCheck"), ENABLE_DESUGAR( "android.enableDesugar", true, DeprecationReporter.DeprecationTarget.DESUGAR_TOOL), ENABLE_INCREMENTAL_DESUGARING( “android.enableIncrementalDesugaring", true, DeprecationReporter.DeprecationTarget.INCREMENTAL_DESUGARING), ENABLE_GRADLE_WORKERS("android.enableGradleWorkers", false), ENABLE_AAPT2_WORKER_ACTIONS( “android.enableAapt2WorkerActions", true), ENABLE_CORE_LAMBDA_STUBS( "android.enableCoreLambdaStubs", true, DeprecationReporter.DeprecationTarget.CORE_LAMBDA_STUBS), ENABLE_D8("android.enableD8", true, DeprecationReporter.DeprecationTarget.LEGACY_DEXER),

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AndroidProject.PROPERTY_REFRESH_EXTERNAL_NATIVE_MODEL, status = Option.Status.STABLE), IDE_GENERATE_SOURCES_ONLY( AndroidProject.PROPERTY_GENERATE_SOURCES_ONLY, status = Option.Status.STABLE), ENABLE_SEPARATE_APK_RESOURCES("android.enableSeparateApkRes", true), ENABLE_EXPERIMENTAL_FEATURE_DATABINDING( "android.enableExperimentalFeatureDatabinding", false), ENABLE_SEPARATE_R_CLASS_COMPILATION( "android.enableSeparateRClassCompilation"), ENABLE_JETIFIER("android.enableJetifier", false, status = Option.Status.STABLE), USE_ANDROID_X("android.useAndroidX", false, status = Option.Status.STABLE), ENABLE_UNIT_TEST_BINARY_RESOURCES( "android.enableUnitTestBinaryResources", false), DISABLE_EARLY_MANIFEST_PARSING(

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~/.gradle/gradle.properties org.gradle.caching=true

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~/.gradle/gradle.properties org.gradle.caching=true …/build.gradle kapt { useBuildCache true }

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~/.gradle/gradle.properties org.gradle.caching=true …/build.gradle kapt { useBuildCache !isCi }

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variantFilter { }a

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variantFilter { variant -> if (variant.flavors[0].name == 'production' && variant.buildType.name == 'debug') { variant.ignore = true } }a

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$ ./gradlew app:assembleDebug --profile

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http://bit.ly/sdk-search-graph

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Deep Dive into the Android Gradle Plugin @jrodbx