Retrolambda

Retrolambda的功能如官方所描述的那样

Retrolambda lets you run Java 8 code with lambda expressions, method references and try-with-resources statements on Java 7, 6 or 5.

使Java 7，6，5支持Java 8中的lambda表达式，方法引用，try-with-resources语句等特性。

JDK 8

安装JDK 8，并将其设置为默认JDK

Gradle Retrolambda Plugin

在Android Studio中使用Retrolambda最方便的方式是使用gradle-retrolambda插件

build.gradle

修改app模块下的build.gradle文件

buildscript {
    repositories {
        mavenCentral()
    }

    dependencies {
        classpath 'me.tatarka:gradle-retrolambda:3.6.1'
    }
}

// Required because retrolambda is on maven central
repositories {
    mavenCentral()
}

apply plugin: 'me.tatarka.retrolambda'
...
android {
    compileOptions {
        targetCompatibility JavaVersion.VERSION_1_8
        sourceCompatibility JavaVersion.VERSION_1_8
    }
    ...
}

使用

package me.zongren.retrolambdademo;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        TextView textView = (TextView)findViewById(R.id.textView);
        //lambda
        textView.setOnClickListener(view -> clickTextView(view));
        //method reference
        textView.setOnClickListener(this::clickTextView);
    }

    private void clickTextView(View view) {

    }
}

官方文档

Oracle官方文档可以看这里：Lambda Expressions，Method References，The try-with-resources Statement

Demo

RetrolambdaDemo