Kotlin in Action, Second Edition

Expert guidance and amazing examples from Kotlin core developers! It’s everything you need to get up and running fast.

Kotlin in Action, Second Edition takes you from language basics to building production-quality applications that take advantage of Kotlin’s unique features. Discover how the language handles everything from statements and functions to classes and types, and the unique features that make Kotlin programming so seamless.

In Kotlin in Action, Second Edition you will learn:

• Kotlin statements and functions, and classes and types
• Functional programming on the JVM
• The Kotlin standard library and out-of-the-box features
• Writing clean and idiomatic code
• Combining Kotlin and Java
• Improve code reliability with null safety
• Domain-specific languages
• Kotlin coroutines and flows
• Mastering the kotlinx.coroutines library

Kotlin in Action, Second Edition is a complete guide to the Kotlin language written especially for readers familiar with Java or another OO language. Its authors—all core Kotlin language developers and Kotlin team members—share their unique insights, along with practical techniques and hands-on examples. This new second edition is fully updated to include the latest innovations, and it adds new chapters dedicated to coroutines, flows, and concurrency.

About the technology

Kotlin is a low-hassle, high-productivity programming language flexible enough to handle any web, mobile, cloud, and enterprise application. Java developers will appreciate the simple syntax, intuitive type system, excellent tooling, and support for functional-style programming. Plus, since Kotlin runs on the JVM, it integrates seamlessly with existing Java code, libraries, and frameworks, including Spring and Android.

About the book

Kotlin in Action, Second Edition teaches you Kotlin techniques you can use for almost any type of application, from enterprise services to Android apps. The authors are all members of the Kotlin team, so you can trust that even the gnarly details are dead accurate. You’ll start with Kotlin fundamentals, learning how the language handles everything from statements and functions to classes and types, and about its unique features that make Kotlin programming so seamless.

As you progress through this masterful book, you’ll get hands-on with the Kotlin standard library, functional programming in Kotlin, and advanced features such as generics and reflection. And this updated second edition now covers coroutines and structured concurrency to help you create efficient high-performance applications.

What's inside

• Guidance from members of the Kotlin team
• Domain-specific languages
• Kotlin coroutines and flows

About the reader

For readers familiar with Java or another OO language.

About the author

Sebastian Aigner is a Developer Advocate at JetBrains, and host of the Talking Kotlin podcast. Roman Elizarov was the lead designer of the Kotlin language. JetBrains Developer Advocate, Svetlana Isakova, was a member of the Kotlin compiler team. Dmitry Jemerov is one of Kotlin’s initial developers.

Table of Contents

PART 1
1 Kotlin: What and why
2 Kotlin basics
3 Defining and calling functions
4 Classes, objects, and interfaces
5 Programming with lambdas
6 Working with collections and sequences
7 Working with nullable values
8 Basic types, collections, and arrays
PART 2
9 Operator overloading and other conventions
10 Higher-order functions: Lambdas as parameters and return values
11 Generics
12 Annotations and reflection
13 DSL construction
PART 3
14 Coroutines
15 Structured concurrency
16 Flows
17 Flow operators
18 Error handling and testing
APPENDIXES
A Building Kotlin projects
B Documenting Kotlin code
C The Kotlin ecosystem

Roman Elizarov is a Project Lead for Kotlin at JetBrains and currently focuses on the Kotlin language design in the role of Lead Language Designer. Roman Elizarov previously designed and developed high-performance trading software for leading brokerage firms and market data delivery services that routinely handle millions of events per second. He has been working on Kotlin at JetBrains since 2016 and has contributed to the design of Kotlin coroutines and the development of the Kotlin coroutines library.

Svetlana Isakova began as a member of the Kotlin compiler team and is now a developer advocate for JetBrains. She teaches Kotlin and speaks at conferences worldwide. She is a co-creator of the course "Kotlin for Java developers" at Coursera and is a co-author of the book "Atomic Kotlin."

As a Kotlin Developer Advocate at JetBrains, Sebastian Aigner spends a lot of time thinking about how technologies can empower and delight people. When he first tried Kotlin, it was love at first sight.He gave talks at KotlinConf, participated in the Kotlin/Everywhere campaign, and spoke at a multitude of other conferences. He hosts the Talking Kotlin podcast together with Hadi Hariri, and creates videos for the official Kotlin YouTube channel.

Dmitry Jemerov has been working with JetBrains since 2003. He was one of the initial developers working on Kotlin as the project was started, and he’s deeply familiar with the design of the language and the reasons for the decisions that were made during its development. He’s currently responsible for Kotlin documentation.