Kotlin was designed to be very similar to Java to make migration as smooth as possible. However, Kotlin was also designed to improve the developers’ experience by providing a more expressive syntax and a more sophisticated type system. To take full advantage of the language and write more concise code, learning Kotlin idioms is a must. Without them, it is easy to fall back into old Java patterns.
So, where do you begin? In this blog post, we would like to highlight some good places to start on the path to learning idiomatic Kotlin.
Source: Useful Kotlin Idioms You Should Know, an article by Anton Arhipov.