Android and Lambda

Update on Java 8 language features on Android

Lambda is back ported to older versions of Android.

This is a feature from Android Gradle Plugin 3.0 and above, lambda is back ported to older Android OS versions as part of other Java 8 language features.

Add this to your Gradle build scripts to enable the feature.

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

For more details, see Use Java 8 language features, and Android' Java 8 support.

As @dhke said, there's no support for Java 8 on Android yet.

Use Java 8, Build For Java 6/7

But you can still use JDK 8 to develop Android application. You just need to set source compatibility to either 6 or 7 depends on your minSDKVersion. Thus, you would lose any new features introduced in Java 8, like lambda in your case.

Backport of Lamda

Since you have extensive usage of lambda, Retrolambda might be an option for you. It provides backport of lambda for pre-Java 8 versions. It has Maven/Gradle/command line plugin to enable the support.

Other Backports

If you need other Java 8 features, AFAIK, ThreeTen ABP provides backport support for Java 8 Date Time API.


I don't think this is going to work.

In order to use lambdas, you need source compatibility level 1.8. In order for the DEX compiler to work you need target compatibility 1.7. Eclipse is not going to let you set the target compatibility below the source compatibility (picture below).

Note that this is unrelated to IntelliJ's habit of thinking it knows way better than you do, what your code should look like. It can show you a lambda, even when the actual code is an anonymous class.

enter image description here


You cannot currently (as up to at least Android 5.1.1) use lambda functions on Android.

Lambda functions require new Dalvik (not necessarily JVM!) opcodes (liberate-variable, box-lambda, unbox-lambda, capture-variable, create-lambda, invoke-lambda) that neither Dalvik nor ART currently have support for.

It looks like google might have scheduled (though nothing seems to be official yet) Java 8 support for post 5.1.1 (API Level 23 and later). At least the smali disassembler already added support with a distinct reference to the API level:

https://github.com/JesusFreke/smali/commit/144951a9e9e6c87866245f2bdeebf0ebedaa0e38:

Add new -X/--experimental flag to [dis]assemble opcodes not in art yet

  • Add new opcodes liberate-variable, box-lambda, unbox-lambda, capture-variable, create-lambda, invoke-lambda
  • Add support for encoding 25x instructions
  • Adds LambdaTest to check new opcodes assemble/disassemble properly

And also

https://github.com/JesusFreke/smali/commit/144951a9e9e6c87866245f2bdeebf0ebedaa0e38#diff-5d7892344c0b747d3667bf8623c690c5R66

options.apiLevel = 23;  // since we need at least level 23 for lambda opcodes

This only marks the opcodes, not the necessary library changes. It also does not tell us anything about Android itself, so I'd suggest not to take this as an official release schedule.


Android does support Java 8, so no only is this not a duplicate

As of Android N preview release Android support limited features of Java 8 see Java 8 Language Features

To start using these features, you need to download and set up Android Studio 2.1 and the Android N Preview SDK, which includes the required Jack toolchain and updated Android Plugin for Gradle. If you haven't yet installed the Android N Preview SDK, see Set Up to Develop for Android N.

Supported Java 8 Language Features and APIs

Android does not currently support all Java 8 language features. However, the following features are now available when developing apps targeting the Android N Preview:

Default and static interface methods

Lambda expressions

Repeatable annotations

There are some additional Java 8 features which Android support, you can see complete detail from Java 8 Language Features

Tags:

Java

Lambda

Eclipse

Android

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