It's also worth noting that you can convert Java into Kotlin by simply pasting Java code into a Kotlin file. When Java is pasted into IntelliJ or Android Studio, you'll be presented with the following dialog:
If you click YES, a Kotlin implementation of the pasted Java code will be generated and will be available to use. This is one of the easiest ways to start working with Kotlin and to understand how to start writing Kotlin code. The ease with which Java can be converted into Kotlin greatly reduces the barrier to entry for teams and individuals looking to start incorporating the Kotlin language into their project.