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

Hot and Cold Observables


So, as we have a grip on the basic concepts of Observables and Observers by now, let's move to something more interesting and advanced. The Observables that we are talking all about can be categorized into two categories based on their behavior. As the heading suggests, the two categories are Hot Obervables and Cold Observable. I can bet that, by now, you are craving to know more about Hot and Cold Observables, aren't you? So, let's dive into it.

Cold Observables

Take a careful look at all the previous examples. In all the examples, if you subscribe to the same Observable multiple times, you will get the emissions from the beginning for all the subscriptions. Don't believe it? Take a look at the following example:

    fun main(args: Array<String>) { 
      val observable: Observable<String> = listOf
      ("String 1","String 2","String 3","String 4").toObservable()//1 
 
      observable.subscribe({//2 
        println("Received $it") 
      },{ 
      ...