feat(android): target Java8 and Kotlin support for native modules

android/app/build.gradle

@@ -29,6 +29,10 @@ android {
 			]
 		}
 	}
+	compileOptions {
+		sourceCompatibility JavaVersion.VERSION_1_8
+		targetCompatibility JavaVersion.VERSION_1_8
+	}
 }
 
 dependencies {

android/build.gradle

@@ -6,12 +6,15 @@
  */
 
 buildscript {
+	ext.kotlin_version = '1.3.61'
+
 	repositories {
 		google()
 		jcenter()
 	}
 	dependencies {
 		classpath 'com.android.tools.build:gradle:3.4.2'
+		classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
 	}
 }
 

android/kroll-apt/build.gradle

@@ -7,8 +7,8 @@
 
 apply plugin: 'java'
 
-sourceCompatibility = JavaVersion.VERSION_1_7
-targetCompatibility = JavaVersion.VERSION_1_7
+sourceCompatibility = JavaVersion.VERSION_1_8
+targetCompatibility = JavaVersion.VERSION_1_8
 
 tasks.withType(JavaCompile) {
 	// Suppress compiler warning "bootstrap class path not set in conjunction with source" which happens when

android/kroll-apt/src/main/java/org/appcelerator/kroll/annotations/generator/KrollJSONGenerator.java

@@ -36,7 +36,7 @@
 
 import org.json.simple.JSONValue;
 
-@SupportedSourceVersion(SourceVersion.RELEASE_7)
+@SupportedSourceVersion(SourceVersion.RELEASE_8)
 @SuppressWarnings("unchecked")
 // clang-format off
 @SupportedAnnotationTypes({

android/templates/build/app.build.gradle

@@ -28,10 +28,9 @@ android {
 		}
 <% } %>
 	}
-	// TODO: Add Java 8 support in the future.
 	compileOptions {
-		sourceCompatibility JavaVersion.VERSION_1_7
-		targetCompatibility JavaVersion.VERSION_1_7
+		sourceCompatibility JavaVersion.VERSION_1_8
+		targetCompatibility JavaVersion.VERSION_1_8
 	}
 	signingConfigs {
 		def tiKeystoreFilePath = <%- "'" + tiSdkAndroidDir.replace(/\\/g, '\\\\') + "/dev_keystore'" %>

android/templates/build/root.build.gradle

@@ -1,11 +1,14 @@
 
 buildscript {
+	ext.kotlin_version = '1.3.61'
+
 	repositories {
 		google()
 		jcenter()
 	}
 	dependencies {
 		classpath 'com.android.tools.build:gradle:3.4.2'
+		classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
 	}
 }
 

android/templates/module/generated/build.gradle

@@ -1,6 +1,8 @@
 
 apply plugin: 'com.android.library'
 apply plugin: 'maven-publish'
+apply plugin: 'kotlin-android'
+apply plugin: 'kotlin-kapt'
 
 repositories {
 	maven {
@@ -118,17 +120,21 @@ android {
 			}
 		}
 	}
-	// TODO: Add Java 8 support in the future.
+
 	compileOptions {
-		sourceCompatibility JavaVersion.VERSION_1_7
-		targetCompatibility JavaVersion.VERSION_1_7
+		sourceCompatibility JavaVersion.VERSION_1_8
+		targetCompatibility JavaVersion.VERSION_1_8
 	}
 	// Exclude the C++ runtime and Titanium kroll libraries for all architectures when packaging the AAR file.
 	// Avoids app build failure due to library file name collision. (Apps will use "titanium.aar" bundled *.so files.)
 	packagingOptions {
 		exclude '/lib/**/libc++_shared.so'
 		exclude '/lib/**/libkroll-v8.so'
 	}
+	// Sets the JVM target in order to allow usage of Java 8 features in Kotlin native modules.
+	kotlinOptions {
+		jvmTarget = '1.8'
+	}
 }
 
 tasks.withType(JavaCompile) {
@@ -153,17 +159,23 @@ tasks.withType(JavaCompile) {
 	}
 }
 
+// Titanium does not support incremental @Kroll annotation processing. Disable it in kotlin to avoid build warnings.
+project.ext['kapt.incremental.apt'] = false
+
 dependencies {
 	// This reads the code's @Kroll annotations and generates code which interops between V8 and proxy classes.
 	def krollAptJarPath = '<%- krollAptJarPath.replace(/\\/g, '\\\\') %>'
 	annotationProcessor files(krollAptJarPath)
 	compileOnly files(krollAptJarPath)
+	kapt files(krollAptJarPath)
 
 	// Reference this module's local AAR/JAR file dependencies.
 	implementation fileTree(dir: "${projectDir}/../../lib", include: ['*.aar', '*.jar'])
 
 	// Reference the main Titanium library.
 	implementation 'org.appcelerator:titanium:<%- tiSdkVersion %>'
+
+	implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk8:$kotlin_version"
 }
 
 // This block is used when we run "gradlew :module:publish" at the command line.

android/titanium/build.gradle

@@ -103,10 +103,9 @@ android {
 			]
 		}
 	}
-	// TODO: Add Java 8 support in the future.
 	compileOptions {
-		sourceCompatibility JavaVersion.VERSION_1_7
-		targetCompatibility JavaVersion.VERSION_1_7
+		sourceCompatibility JavaVersion.VERSION_1_8
+		targetCompatibility JavaVersion.VERSION_1_8
 	}
 }