Book Image

Learning RxJava - Second Edition

By : Nick Samoylov, Thomas Nield
Book Image

Learning RxJava - Second Edition

By: Nick Samoylov, Thomas Nield

Overview of this book

RxJava is not just a popular library for building asynchronous and event-based applications; it also enables you to create a cleaner and more readable code base. In this book, you’ll cover the core fundamentals of reactive programming and learn how to design and implement reactive libraries and applications. Learning RxJava will help you understand how reactive programming works and guide you in writing your first example in reactive code. You’ll get to grips with the workings of Observable and Subscriber, and see how they are used in different contexts using real-world use cases. The book will also take you through multicasting and caching to help prevent redundant work with multiple Observers. You’ll then learn how to create your own RxJava operators by reusing reactive logic. As you advance, you’ll explore effective tools and libraries to test and debug RxJava code. Finally, you’ll delve into RxAndroid extensions and use Kotlin features to streamline your Android apps. By the end of this book, you'll become proficient in writing reactive code in Java and Kotlin to build concurrent applications, including Android applications.
Table of Contents (22 chapters)
1
Section 1: Foundations of Reactive Programming in Java
5
Section 2: Reactive Operators
12
Section 3: Integration of RxJava applications
Appendix B: Functional Types
Appendix E: Understanding Schedulers

Suppressing operators

There are operators that suppress emissions that do not meet a specified criterion. These operators work by simply not calling the onNext() function downstream for a disqualified emission, and therefore it does not go down the chain to Observer. We have already seen the filter() operator, which is probably the most common suppressing operator. We will start with this one.

filter()

The filter() operator accepts Predicate<T> for a given Observable<T>. This means that you provide it a lambda that qualifies each emission by mapping it to a Boolean value, and emissions with false will not go downstream.

For instance, you can use filter() to only allow string emissions that are not five characters...