在Android中引入Java8的lambda表达式

我用的是retrolambda这个插件，下面来说下如何添加它。

项目地址：https://github.com/evant/gradle-retrolambda

在根项目的build.gradle中添加这个classpath

classpath 'me.tatarka:gradle-retrolambda:3.2.0'//retrolambda

example：

buildscript {
    repositories {
        jcenter()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:1.2.3'
        classpath 'me.tatarka:gradle-retrolambda:3.2.0'//retrolambda
        // NOTE: Do not place your application dependencies here; they belong
        // in the individual module build.gradle files
    }
}

allprojects {
    repositories {
        jcenter()
    }
}

然后，在项目的bulid.gradle中添加插件，并让其使用java8

apply plugin: 'com.android.application'
apply plugin: 'me.tatarka.retrolambda'

android {
    compileSdkVersion rootProject.compileSdkVersion
    buildToolsVersion rootProject.buildToolsVersion

    defaultConfig {
        applicationId "kale.androidframework"
        minSdkVersion rootProject.minSdkVersion
        targetSdkVersion rootProject.targetSdkVersion
        versionCode Integer.parseInt(project.VERSION_CODE)
        versionName project.VERSION_NAME
    }

    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.txt'
        }
    }

    lintOptions {
        checkReleaseBuilds false
        // Or, if you prefer, you can continue to check for errors in release builds,
        // but continue the build even when errors are found:
        abortOnError false
    }

    compileOptions {
        sourceCompatibility JavaVersion.VERSION_1_8
        targetCompatibility JavaVersion.VERSION_1_8
    }
}

retrolambda {
    javaVersion JavaVersion.VERSION_1_7
}

//设置编码
tasks.withType(JavaCompile) {
    options.encoding = "UTF-8"
}

dependencies {
    compile fileTree(include: ['*.jar'], dir: 'libs')
}

如果你用到了多个lib库，需要在每个lib中进行添加：

apply plugin: 'me.tatarka.retrolambda'

android {

  compileOptions {
    sourceCompatibility JavaVersion.VERSION_1_8
    targetCompatibility JavaVersion.VERSION_1_8
  }

}