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


As we discussed earlier, in reactive programming, Observable has an underlying computation that produces values that can be consumed by a consumer (Observer). The most important thing here is that the consumer (Observer) doesn't pull values here; rather, Observable pushes the value to the consumer. So, we may say, an Observable is a push-based, composable iterator that emits its items through a series of operators to the final Observer, which finally consumes the items. Let's now break things sequentially to understand it better:

  • Observer subscribes to Observable
  • Observable starts emitting items that it has in it
  • Observer reacts to whatever item Observable emits

So, let's delve into how an Observable works through its events/methods, namely, onNext, onComplete, and onError.

How Observable works

As we stated earlier, an Observable has three most important events/methods; let's discuss them one by one:

  • onNext: Observable passes all items one by one to this method.
  • onComplete: When all...