Android development become increasingly Kotlin-first

At Google I/O'19, Google announced Android development will become increasingly Kotlin-first. Many new Jetpack APIs and features will be offered first in Kotlin. If you’re starting a new project, you should write it in Kotlin.

What's New in Kotlin on Android, 2 Years In (Google I/O'19)
This session examines the progress made in Android support for Kotlin. This talk will cover Kotlin samples and reference docs, annotations, framework APIs, IDE support for low-level bytecode optimizations in the D8/R8 compiler, and work on the Kotlin Foundation.