Book Review: Kotlin in Action

Book ReviewKotlin
Kotlin in Action

Kotlin has been an obsession of mine for the last two years. I remember advocating for immutable data and using streams in a project I was on, where we were stuck with Java. Switching to Kotlin was such a breath of fresh air. This is the book that helped me during that period.

I would say the ideal target audience is folks who are already familiar with Java and want to learn Kotlin. You’ll get started faster, and you’ll be able to appreciate how much more concise and usable Kotlin is. That seems to be a common origin for most people learning Kotlin, but in any case, you should be able to pick it up regardless of your background, as long as you do have some experience programming.

Learning Kotlin

This book focuses on introducing you to Kotlin, from its syntax to features like nullable types, collections, or operators. The later chapters are dedicated to some more advanced concepts, like reflection or building DSLs. Interestingly, coroutines don’t make an appearance.

As usual with learning a new programming language, a healthy combination of reading and practicing is advisable. Given that there are no exercises to practice in the book, I recommend exercism to get started and the Kotlin Tapas I shared some time ago.

The book doesn’t make assumptions about your target environment. Whether you want to do backend development or mobile, it is the right place to get acquainted with the basic constructs of the language. It is written by two members of the core development team of Kotlin, who are knowledgeable about the language and present it in a clear and approachable way.

Next steps

As I mentioned, this book functions as an introduction to the language. If you want to explore it further, I liked The joy of Kotlin, which is definitely not an introduction book. I’ve heard good things about Effective Kotlin, although I haven’t read that one myself.


An excellent way of getting started with Kotlin. It doesn’t go too much into idiomatic Kotlin, however. Nevertheless, it’s worth ⭐⭐⭐⭐ stars for me.