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

The Observer interface


The onNext(), onComplete(), and onError() methods actually define the Observer type, an abstract interface implemented throughout RxJava to communicate these events. This is the Observer definition in RxJava shown in the code snippet. Do not bother yourself about onSubscribe() for now, as we will cover it at the end of this chapter. Just bring your attention to the other three methods:

    package io.reactivex;

    import io.reactivex.disposables.Disposable;

    public interface Observer<T> {
      void onSubscribe(Disposable d);
      void onNext(T value);
      void onError(Throwable e);
      void onComplete();
   }

Observers and source Observables are somewhat relative. In one context, a source Observable is where your Observable chain starts and where emissions originate. In our previous examples, you could say that the Observable returned from our Observable.create() method or Observable.just() is the source Observable. But to the filter() operator, the...