All kotlin collection types are essentially Java ones (at least for a JVM target), the difference is that the IDE and compiler are smart about its type inferenc

All kotlin collection types are essentially Java ones (at least for a JVM target), the difference is that the IDE and compiler are smart about its type inference system so that it can tell when a variable use is nullable or not. Java has come a long way in recent years and it's far better than it was in the past. Kotlin stands on the great baseline of features that Java has established and there are certainly many advantages to (mostly ergonomics), to using Kotlin over Java at least for the time being.