Book Image

Reactive Programming in Kotlin

By : Rivu Chakraborty
Book Image

Reactive Programming in Kotlin

By: Rivu Chakraborty

Overview of this book

In today's app-driven era, when programs are asynchronous, and responsiveness is so vital, reactive programming can help you write code that's more reliable, easier to scale, and better-performing. Reactive programming is revolutionary. With this practical book, Kotlin developers will first learn how to view problems in the reactive way, and then build programs that leverage the best features of this exciting new programming paradigm. You will begin with the general concepts of Reactive programming and then gradually move on to working with asynchronous data streams. You will dive into advanced techniques such as manipulating time in data-flow, customizing operators and provider and how to use the concurrency model to control asynchronicity of code and process event handlers effectively. You will then be introduced to functional reactive programming and will learn to apply FRP in practical use cases in Kotlin. This book will also take you one step forward by introducing you to Spring 5 and Spring Boot 2 using Kotlin. By the end of the book, you will be able to build real-world applications with reactive user interfaces as well as you'll learn to implement reactive programming paradigms in Android.
Table of Contents (20 chapters)
Title Page
About the Author
About the Reviewers
Customer Feedback


We may call Flowables a backpressured version of Observables. Probably, the only difference between Flowables and Observables is that Flowable takes backpressure into consideration. Observable does not. That's it. Flowable hosts the default buffer size of 128 elements for operators, so, when the consumer is taking time, the emitted items may wait in the buffer.


Note that Flowables were added in ReactiveX 2.x (RxKotlin 2.X), and the previous versions don't include them. Instead, in previous versions, Observables was retrofitted to support backpressure that caused many unexpected MissingBackpressureException. Here is the release note if you are interested:

We had a long discussion so far; let's now try our hands on code. At first, we will try a code with Observable, and then we will do the same with Flowables to see and understand the difference:

    fun main(args: Array<String>) {