Reactive Programming in Kotlin

Introduction

The book "Reactive Programming in Kotlin" by Rivu Chakraborty, published in 2017, is one of the first comprehensive guides to reactive programming in the Kotlin language. In an era where asynchrony and data stream processing have become an integral part of modern development, this book offers a systematic approach to mastering reactive paradigms using the RxKotlin library (and its predecessor RxJava). Although several years have passed since its release, the fundamental concepts laid out in the book remain relevant today, especially for developers transitioning from Java to Kotlin or those looking to deepen their understanding of reactive patterns.

What the book is about

The book covers the full cycle of working with reactive streams: from basic concepts (Observable, Observer, Scheduler) to complex scenarios of combining, transforming, and error handling. The author consistently introduces the reader to the main building blocks of RxKotlin, such as Flowable, Single, Maybe, and Completable, as well as transformation operators (map, flatMap, filter, reduce, etc.). Special attention is paid to integrating the reactive approach with existing Java libraries and frameworks, making the book useful for developers working on mixed projects.

Who this book is for

The book is intended for developers who already have basic programming experience in Kotlin or Java. It will be useful for:

• Android developers looking to master reactive chains for managing UI events and network requests;
• Backend developers working with Kotlin, asynchronous APIs, and stream data processing;
• Java developers transitioning to Kotlin who want to understand how reactive patterns are implemented in the new language;
• Students and beginners who want to understand reactive programming from scratch.

What the reader will learn

After studying the book, the reader will be able to:

• Understand the principles of reactive programming and how it differs from the imperative approach;
• Create and combine reactive streams using RxKotlin;
• Manage multithreading with Schedulers;
• Handle errors in reactive chains (retry, onErrorReturn, onErrorResumeNext);
• Use transformation and filtering operators for data processing;
• Integrate RxKotlin with popular libraries (Retrofit, Room, etc.);
• Test reactive code using TestScheduler and special utilities;
• Design application architecture based on reactive patterns (MVVM with Rx).

Strengths

The main advantage of the book is its practical focus. Each chapter contains numerous code examples that can be immediately run and modified. The author doesn't just list operators but explains which one is best to apply in which situation. Special mention should be made of the chapters dedicated to testing and debugging reactive code — this is rare for books on reactive programming. Moreover, the book is written in a lively style; complex concepts (e.g., backpressure or hot/cold Observable) are explained using clear analogies.

Who it is recommended for

I strongly recommend this book to anyone who wants to systematically learn reactive programming in Kotlin, rather than just copy a few examples from the internet. It will be useful both for beginners taking their first steps in the reactive world and for experienced developers looking to structure their knowledge. If you write in Kotlin and encounter asynchronous calls, multithreading, or complex event processing scenarios — this book will become your reliable assistant.