/gradle-android-scala-plugin

gradle-android-scala-plugin adds scala language support to official gradle android plugin

Primary LanguageJavaApache License 2.0Apache-2.0

gradle-android-scala-plugin Build Status

gradle-android-scala-plugin adds scala language support to official gradle android plugin. See also sample projects at https://github.com/saturday06/gradle-android-scala-plugin/tree/master/sample

Table of Contents generated with DocToc

Supported versions

Scala Gradle Android Plugin compileSdkVersion buildToolsVersion
2.11.5 2.2.1 1.0.0 - 1.0.1 android-21 21.1.1 - 21.1.2
2.10.4 2.2.1 1.0.0 - 1.0.1 android-21 21.1.1 - 21.1.2
2.11.5 1.12 0.12.2 android-21 21.1.1 - 21.1.2
2.10.4 1.12 0.12.2 android-21 21.1.1 - 21.1.2
2.11.5 1.12 0.12.2 android-19 19.1.0
2.10.4 1.12 0.12.2 android-19 19.1.0

Installation

1. Add buildscript's dependency

build.gradle

buildscript {
    dependencies {
        classpath "com.android.tools.build:gradle:1.0.1"
        classpath "jp.leafytree.gradle:gradle-android-scala-plugin:1.3.2"
    }
}

2. Apply plugin

build.gradle

apply plugin: "com.android.application"
apply plugin: "jp.leafytree.android-scala"

3. Add scala-library dependency

The plugin decides scala language version using scala-library's version.

build.gradle

dependencies {
    compile "org.scala-lang:scala-library:2.11.5"
}

4. Put scala source files

Default locations are src/main/scala, src/androidTest/scala. You can customize those directories similar to java.

build.gradle

android {
    sourceSets {
        main {
            scala {
                srcDir "path/to/main/scala" // default: "src/main/scala"
            }
        }

        androidTest {
            scala {
                srcDir "path/to/androidTest/scala" // default: "src/androidTest/scala"
            }
        }
    }
}

5. Implement a workaround for DEX 64K Methods Limit

The Scala Application generally suffers DEX 64K Methods Limit. To avoid it we need to implement one of following workarounds.

5.1. Option 1: Use ProGuard

If your project doesn't need to run androidTest, You can use proguard to reduce methods.

Sample proguard configuration here:

proguard-rules.txt

-dontoptimize
-dontobfuscate
-dontpreverify
-dontwarn scala.**
-ignorewarnings
# temporary workaround; see Scala issue SI-5397
-keep class scala.collection.SeqLike {
    public protected *;
}

From: hello-scaloid-gradle

5.2. Option 2: Setup MultiDexApplication manually

If your project needs to run androidTest, You should setup MultiDexApplication manually. See also https://github.com/casidiablo/multidex . There is multiDexEnabled option but it can't be used because it causes DexException: Too many classes in --main-dex-list, main dex capacity exceeded .

NOTE: Use of multidex for creating a test APK is not currently supported. Described in google's documentation

build.gradle

repositories {
    jcenter()
}

android {
    dexOptions {
        preDexLibraries false
        javaMaxHeapSize "2g"
    }
}

dependencies {
    compile "com.android.support:multidex:1.0.0"
    compile "org.scala-lang:scala-library:2.11.5"
}

afterEvaluate {
    tasks.matching {
        it.name.startsWith("dex")
    }.each { dx ->
        dx.additionalParameters = (dx.additionalParameters ?: []) + [
            "--multi-dex",
            "--main-dex-list=$rootDir/main-dex-list.txt".toString(),
        ]
    }
}

Add main dex configuration.

main-dex-list.txt

android/support/multidex/BuildConfig.class
android/support/multidex/MultiDex$V14.class
android/support/multidex/MultiDex$V19.class
android/support/multidex/MultiDex$V4.class
android/support/multidex/MultiDex.class
android/support/multidex/MultiDexApplication.class
android/support/multidex/MultiDexExtractor$1.class
android/support/multidex/MultiDexExtractor.class
android/support/multidex/ZipUtil$CentralDirectory.class
android/support/multidex/ZipUtil.class
com/android/test/runner/MultiDexTestRunner.class

Change application class.

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android" package="jp.leafytree.sample">
    <application android:name="android.support.multidex.MultiDexApplication">
</manifest>

If you use customized application class, please read next section.

To test MultiDexApplication, custom instrumentation test runner should be used. See also https://github.com/casidiablo/multidex/blob/publishing/instrumentation/src/com/android/test/runner/MultiDexTestRunner.java

build.gradle

android {
  defaultConfig {
    testInstrumentationRunner "com.android.test.runner.MultiDexTestRunner"
  }
}

src/androidTest/java/com/android/test/runner/MultiDexTestRunner.java

package com.android.test.runner;

import android.os.Bundle;
import android.support.multidex.MultiDex;
import android.test.InstrumentationTestRunner;

public class MultiDexTestRunner extends InstrumentationTestRunner {
    @Override
    public void onCreate(Bundle arguments) {
        MultiDex.install(getTargetContext());
        super.onCreate(arguments);
    }
}
5.2.1. Setup application class if you use customized one

Since application class is executed before multidex configuration, Writing custom application class has stll many pitfalls.

The application class must extend MultiDexApplication or override Application#attachBaseContext like following.

MyCustomApplication.scala

package my.custom.application

import android.app.Application
import android.content.Context
import android.support.multidex.MultiDex
import my.custom.application.main.{ClassNotNeededToBeListed, ClassNeededToBeListed}

object MyCustomApplication {
  var globalVariable: Int = _
}

class MyCustomApplication extends Application {
  override protected def attachBaseContext(base: Context) = {
    super.attachBaseContext(base)
    MultiDex.install(this)
  }

  var variable: ClassNeededToBeListed = _
}

Add your customized application class to main-dex-list.txt.

main-dex-list.txt

android/support/multidex/BuildConfig.class
android/support/multidex/MultiDex$V14.class
android/support/multidex/MultiDex$V19.class
...
my/custom/application/MyCustomApplication.class
my/custom/application/MyCustomApplication$$anon$1.class
my/custom/application/main/ClassNeededToBeListed.class

You need to remember:

NOTE: The following cautions must be taken only on your android Application class, you don't need to apply this cautions in all classes of your app

  • The static fields in your application class will be loaded before the MultiDex#installbe called! So the suggestion is to avoid static fields with types that can be placed out of main classes.dex file.
  • The methods of your application class may not have access to other classes that are loaded after your application class. As workaround for this, you can create another class (any class, in the example above, I use Runnable) and execute the method content inside it. Example:
  override def onCreate = {
    super.onCreate

    val context = this
    new Runnable {
      override def run = {
        variable = new ClassNeededToBeListed(context, new ClassNotNeededToBeListed)
        MyCustomApplication.globalVariable = 100
      }
    }.run
  }

This section is copyed from README.md for multidex project

Configuration

You can configure scala compiler options as follows:

build.gradle

tasks.withType(ScalaCompile) {
    // If you want to use scala compile daemon
    scalaCompileOptions.useCompileDaemon = true
    // Suppress deprecation warnings
    scalaCompileOptions.deprecation = false
    // Additional parameters
    scalaCompileOptions.additionalParameters = ["-feature"]
}

Complete list is described in http://www.gradle.org/docs/current/dsl/org.gradle.api.tasks.scala.ScalaCompileOptions.html

Complete example of build.gradle with manually configured MultiDexApplication

build.gradle

buildscript {
    repositories {
        mavenCentral()
    }

    dependencies {
        classpath "com.android.tools.build:gradle:1.0.1"
        classpath "jp.leafytree.gradle:gradle-android-scala-plugin:1.3.2"
    }
}

repositories {
    jcenter()
}

apply plugin: "com.android.application"
apply plugin: "jp.leafytree.android-scala"

android {
    compileSdkVersion "android-21"
    buildToolsVersion "21.1.2"

    defaultConfig {
        minSdkVersion 8
        targetSdkVersion 21
        testInstrumentationRunner "com.android.test.runner.MultiDexTestRunner"
        versionCode 1
        versionName "1.0"
    }

    sourceSets {
        main {
            scala {
                srcDir "path/to/main/scala" // default: "src/main/scala"
            }
        }

        androidTest {
            scala {
                srcDir "path/to/androidTest/scala" // default: "src/androidTest/scala"
            }
        }
    }

    dexOptions {
        preDexLibraries false
        javaMaxHeapSize "2g"
    }
}

dependencies {
    compile "com.android.support:multidex:1.0.0"
    compile "org.scala-lang:scala-library:2.11.5"
}

tasks.withType(ScalaCompile) {
    scalaCompileOptions.deprecation = false
    scalaCompileOptions.additionalParameters = ["-feature"]
}

afterEvaluate {
    tasks.matching {
        it.name.startsWith("dex")
    }.each { dx ->
        dx.additionalParameters = (dx.additionalParameters ?: []) + [
            "--multi-dex",
            "--main-dex-list=$rootDir/main-dex-list.txt".toString(),
        ]
    }
}

Changelog

  • 1.3.2 Fix unexpected annotation processor's warnings
  • 1.3.1 Support android plugin 12.2
  • 1.3 Incremental compilation support in scala 2.11
  • 1.2.1 Fix binary compatibility with JDK6
  • 1.2 Incremental compilation support in scala 2.10 / Flavors support
  • 1.1 MultiDexApplication support
  • 1.0 First release