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


Before we discuss Subjects, it would be remiss to not highlight, they have use cases but beginners often use them for the wrong ones, and end up in convoluted situations. As you will learn, they are both an Observer and an Observable, acting as a proxy mulitcasting device (kind of like an event bus). They do have their place in reactive programming, but you should strive to exhaust your other options before utilizing them. Erik Meijer, the creator of ReactiveX, described them as the "mutable variables of reactive programming". Just like mutable variables are necessary at times even though you should strive for immutability, Subjects are sometimes a necessary tool to reconcile imperative paradigms with reactive ones.

But before we discuss when to and when not to use them, let's take a look at what they exactly do.


There are a couple implementations of Subject, which is an abstract type that implements both Observable and Observer. This means that you can manually call...