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

Concatenation


Concatenation is remarkably similar to merging, but with an important nuance: it will fire elements of each provided Observable sequentially and in the order specified. It will not move on to the next Observable until the current one calls onComplete(). This makes it great to ensure that merged Observables fire their emissions in a guaranteed order. However, it is often a poor choice for infinite Observables, as an infinite Observable will indefinitely hold up the queue and forever leave subsequent Observables waiting.

We will cover the factories and operators used for concatenation. You will find that they are much like the merging ones except that they have the sequential behavior.

Note

You should prefer concatenation when you want to guarantee that Observables fire their emissions in order. If you do not care about ordering, prefer merging instead.

 

Observable.concat() and concatWith()

The Observable.concat() factory is the concatenation equivalent to Observable.merge(). It will...