Java to Kotlin

Preface

Hello, this is Duncan and Nat. As you’re reading this preface, you’re probably trying to decide whether to invest some hours into reading the rest of this book. So let’s cut to the chase:

This book won’t teach you to program computers in Kotlin.

We started writing a book that would, but it soon became clear that Kotlin is a large language, and so the book was going to take longer to write than we wanted. There are also already some great books in that space, and we don’t like competing against great.

We decided instead to make our lives easier by concentrating on teaching Kotlin to Java developers, based on a workshop that we run called Refactoring to Kotlin. This teaches the Kotlin language by converting existing code and is (according to our marketing material) designed for Java teams wanting to leverage their existing knowledge to accelerate their Kotlin adoption.

We started writing that book, but it soon became clear that Kotlin is still a large language, and so we would still be writing for a long time. We also found that motivated and experienced Java developers can pick up most of Kotlin very quickly. It felt patronizing to plow our way through language features that our target readers will probably just appreciate and adopt as soon as they see them. So we abandoned that idea, and as a result:

This book won’t teach you the Kotlin language.

So why should you read it? Because we have written the book we wish was available when we first adopted Kotlin. We are experienced ...