You don't need to learn Java before you learn Kotlin. As you may notice in your paraphrasing, it doesn't say you need to, it says it's simple if you know Java already.<p>More concretely, what you'll find is that a lot of tutorials and books will likely assume some familiarity with Java. Not necessarily to a point that you can't learn, but more in regards to what they emphasise. For example, they'll likely talk about nullability and Kotlin's approach to it. This makes a lot of sense if you've come from Java but maybe less if you've come from a language that doesn't have nulls.<p>Having said that, I would expect that, although learning Kotlin should be fine, once you start developing in it, you'll soon find that you'll need to have some familiarity with Java. The reason is that a big selling point of Kotlin is its easy integration with Java. As a consequence, you'll probably find that the libraries you'll want, beyond the basics, won't have been ported to Kotlin. As there's not much call for this.<p>Unfortunately, I can't recommend a book for non-Java developers as I don't know any Kotlin developers who weren't Java developers first!