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

Transformers


When working with RxJava, you may find yourself wanting to reuse pieces of an Observable or Flowable chain and somehow consolidate these operators into a new operator. Good developers find opportunities to reuse code, and RxJava provides this ability using ObservableTransformer and FlowableTransformer, which you can pass to the compose() operator.

ObservableTransformer

Bring back Google Guava as a dependency. In Chapter 3, Basic Operators, we covered the collect() operator and used it to turn  Observable<T> into a Single<ImmutableList<T>>. Effectively, we want to collect T emissions into a Google Guava ImmutableList<T>. Suppose we do this operation enough times until it starts to feel redundant. Here, we use this ImmutableList operation for two different Observable subscriptions:

 import com.google.common.collect.ImmutableList;
 import io.reactivex.Observable;

 public class Launcher {

     public static void main(String[] args) {

         Observable...