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
Credits
About the Author
About the Reviewers
www.PacktPub.com
Customer Feedback
Dedication
Preface

Grouping


Grouping is a powerful operation that can be achieved using RxKotlin. This operation allows you to group emissions based on their property. Say, for example, you have an Observable / Flowable emitting integer numbers (Int), and, as per your business logic, you have some separate code for even and odd numbers and want to handle them separately. Grouping is the best solution in that scenario.

Let's take an example:

    fun main(args: Array<String>) { 
      val observable = Observable.range(1,30) 
 
      observable.groupBy {//(1) 
        it%5 
      }.blockingSubscribe {//(2) 
        println("Key ${it.key} ") 
        it.subscribe {//(3) 
            println("Received $it") 
        } 
      } 
    } 

In this example, I've grouped emissions based on their remainder when divided by 5, so, basically, there should be 5 groups (0 through 4). On comment (1) of this example, we used the groupBy operator and passed a predicate to it, upon which the grouping should be performed. The...