Kotlin's primary sponsor is JetBrains, the company behind tools like IntelliJ. It's 100 percent interoperable with Java, which until now was Google's only primary language for writing Android apps.

Kotlin may even change how Java is used on the server, the company said: “In short, Android developers without Kotlin skills are at risk of being seen as dinosaurs very soon.” ...

With Kotlin, there is less to type, less to test, and less to maintain, said Chet Haase, who leads the Android UI team at Google, at the Google I/O developer conference in Mountain View, CA.