https://android-developers.googleblog.com/2017/03/future-of-java-8-language-feature.html
We've decided to add support for Java 8 language features directly into the current javac and dx set of tools, and deprecate the Jack toolchain. With this new direction, existing tools and plugins dependent on the Java class file format should continue to work. Moving forward, Java 8 language features will be natively supported by the Android build system. We're aiming to launch this as part of Android Studio in the coming weeks, and we wanted to share this decision early with you.
好不容易把 app 都改成 jack 的人表示心情复杂