Kotlin for Java Developers: Confidently transition from Java to Kotlin through hands-on examples and idiomatic Kotlin practices

Written by José Dimas Luján Castillo and Ron Veen - seasoned developers with deep expertise in Java and Kotlin - this practical guide teaches Kotlin through side-by-side Java comparisons, real-world examples, and clear explanations of modern language features.

Key Features

Learn Kotlin by drawing direct comparisons to core Java concepts

Understand null safety, coroutines, extension functions, and DSLs through practical examples

Use Kotlin confidently in backend, Android, and cross-platform development

Purchase of the print or Kindle book includes a free PDF eBook

Book DescriptionThis book is a hands-on programming guide for Java developers who want to gain practical, production-ready knowledge of Kotlin. Whether you’re maintaining Java systems or adopting Kotlin for Android, backend, or cross-platform projects, it will help you bridge the gap by building on your existing understanding of Java’s syntax and design principles.

You’ll begin by learning why Kotlin was created and how it improves on Java – exploring types, expressions, control flow, and null handling while mapping each concept to familiar Java constructs. Each topic is introduced with clear purpose, showing how Kotlin’s concise syntax, safety features, and expressive APIs lead to cleaner, more maintainable code.

As you progress, you’ll master object-oriented and functional programming, extension functions, smart casting, and interoperability with Java. The second half of the book dives into generics, data and sealed classes, coroutines for concurrency, and DSL design – demonstrating when and why to use these features to build scalable, elegant solutions.

By the end, you’ll not only write idiomatic Kotlin but also understand the reasoning behind its design, enabling you to craft modern, reliable applications with confidence.What you will learn

Write Kotlin programs using variables, functions, and control flow

Model real-world data with classes, properties, and constructors

Handle missing data safely with nullable types and safe calls

Simplify logic using lambdas and extension functions

Work with Kotlin collections and sequences to process data efficiently

Use Kotlin with Java, Gradle, and Maven for seamless project builds

Write non-blocking code using coroutines and Async flows

Create custom DSL for your projects

Who this book is forThis book is for software developers who are proficient in Java and want to learn Kotlin for professional application development. It’s especially relevant for Android engineers, JVM backend developers, and full-stack programmers who maintain or extend Java systems. Familiarity with core Java syntax and object-oriented programming is expected.