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

Using RxJava and RxAndroid


The primary feature of the RxAndroid library (https://github.com/ReactiveX/RxAndroid) is that it has Android Schedulers to help your concurrency goals for your Android app. It has a Scheduler for the Android main thread as well as an implementation that can target any message Looper. Striving to be a core library, RxAndroid does not have many other features. You will need specialized reactive binding libraries for Android to do more than that, which we will explore later.

Let's start simple. We will modify TextView in the middle of our MainActivity (which already contains "Hello World!") to change to "Goodbye World!" after 3 seconds. We will do all of this reactively using Observable.delay(). Because this will emit on a computational Scheduler, we will need to leverage observeOn() to safely switch the emission to the Android main thread.

First, in the res/layout/activity_main.xml file, modify the TextView block to have an ID property called my_text_view (as shown...