Jetbrains has a very good 4 weeks free course on Coursera https://www.coursera.org/learn/kotlin-for-java-developers https://www.coursera.org/learn/kotlin-for-ja

Jetbrains has a very good 4 weeks free course on Coursera https://www.coursera.org/learn/kotlin-for-java-developers https://www.coursera.org/learn/kotlin-for-java-developers. We’ve beginning to introduce Kotlin in our code based, and also begin to use Kotlin Dsl on our new Gradle projects; for the moment, the experience is excellent. Interop with Java is really good and the support from IntelliJ is also fine.