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

Debugging RxJava code

RxJava is not easy to debug at first glance, primarily due to the lack of debug tooling and the large stack traces it can produce. There are efforts in creating effective debugging tools for RxJava, most notably the Frodo library for Android ( We will not cover any debugging tools for RxJava as nothing has been standardized quite yet, but we will learn about an effective approach that you can take to debug reactive code.

A common theme in debugging RxJava operations is finding the bad link or the operator in the Observable/Flowable chain that is causing the problem. Whether an error is being emitted, onComplete() is never being called, or an Observable is unexpectedly empty, you often have to start at the beginning of the chain at the source and then validate each step downstream until you find the one not working correctly.

Say, we have an Observable pushing five strings containing numbers and alphabetic words separated by slashes...