May 2013 - https://blog.jetbrains.com/blog/2013/05/15/intellij-idea-is-the-base-for-android-studio-the-new-ide-for-android-developers/ https://blog.jetbrains.co

May 2013 - https://blog.jetbrains.com/blog/2013/05/15/intellij-idea-is-the-base-for-android-studio-the-new-ide-for-android-developers/ https://blog.jetbrains.com/blog/2013/05/15/intellij-idea-is-... May 2017 - https://www.theverge.com/2017/5/17/15654988/google-jet-brains-kotlin-programming-language-android-development-io-2017 https://www.theverge.com/2017/5/17/15654988/google-jet-brain... You could use Kotlin for years before Google officially endorsed it...given that Android Studio is made by JetBrains and they made it trivial to use. JetBrains did 100% of the heavy lifting, and Google just conceded eventually.