The above is pretty misleading. A typical Java program can be made into a Kotlin program with little changes, this is true. But Kotlin code, particularly when written using Kotlin best practices, bares very little resemblance to Java code. If you learn Kotlin first, you'll find some of that knowledge does transfer to Java but then there's plenty that won't and you'll have to learn the Java way of doing things too. Still, as a dev, knowing more languages never hurts. I'd still recommend proceeding with Kotlin.