Book Image

Learning RxJava

By : Thomas Nield
Book Image

Learning RxJava

By: Thomas Nield

Overview of this book

RxJava is a library for composing asynchronous and event-based programs using Observable sequences for the JVM, allowing developers to build robust applications in less time. Learning RxJava addresses all the fundamentals of reactive programming to help readers write reactive code, as well as teach them an effective approach to designing and implementing reactive libraries and applications. Starting with a brief introduction to reactive programming concepts, there is an overview of Observables and Observers, the core components of RxJava, and how to combine different streams of data and events together. You will also learn simpler ways to achieve concurrency and remain highly performant, with no need for synchronization. Later on, we will leverage backpressure and other strategies to cope with rapidly-producing sources to prevent bottlenecks in your application. After covering custom operators, testing, and debugging, the book dives into hands-on examples using RxJava on Android as well as Kotlin.
Table of Contents (21 chapters)
Title Page
About the Author
About the Reviewers
Customer Feedback

Materializing and Dematerializing

Two interesting operators we did not cover are materialize() and dematerialize(). We did not cover them in Chapter 3Basic Operators, with all the other operators because it might have been confusing at that point in your learning curve. But hopefully, the point at which you are reading this, you understand the onNext(), onComplete(), and onError() events well enough to use an operator that abstractly packages them in a different way.

The materialize() operator will take these three events, onNext(), onComplete(), and onError(), and turn all of them into emissions wrapped in a Notification<T>. So if your source emits five emissions, you will get six emissions where the last one will be onComplete() or onError(). In the following code, we materialize an Observable emitting five strings, which are turned into six Notification emissions:

import io.reactivex.Observable;

public class Launcher {

    public static void main(String[] args) {