Should I learn Kotlin or Java? | Kotlin is Here, and it's Officially Supported now!
TL;DR
Beginners: Learn the basics of Java until you can follow along with Java tutorials. This is because most learning resources for the Android Platform are in Java (especially the more complex topics like RxJava, Dagger 2, and so forth).
Beginner/Intermediate:
If you've got the basics of Java sorted out, and you can follow Java based tutorials, Dive into learning Kotlin! It's too early to tell if it will entirely unseat Java, and it's here to stay (officially supported) and there's plenty of benefit to learning it. Follow your Interests!!!!