see https://developer.android.com/kotlin/index.html
Starting with Android Studio 3.0, tooling support for Kotlin is bundled directly into Android Studio. (其实 早就有了,只是没有官宣)
We believe Kotlin is an excellent fit for Android not only because it gives developers what they want, but also because it matches the spirit of Android.
And while we're adding Kotlin as an official Android language, we're also expanding our investment in our existing languages. For example, in Android O we added support for more Java 8 libraries.
