While writing code in imperative programming languages, programmers take advantage of Reactive Extensions (ReactiveX) to compose event-based and asynchronous programs more efficiently. ReactiveX further make it easier for developers to operate on sequence of synchronous and asynchronous data. Many Java developers and Android programmers ask us what is RxJava. RxJava is an open source implementation of ReactiveX library for java virtual machine (JVM). RxJava is a lightweight implementation, still it supports several widely used JVM-based programming languages – Java, Kotlin, Scala, Groovy, JRuby and Clojure. Interested readers can read more about one of my previous blogs Java vs Scala: which is better.

At present, RxJava finds extensive use by Android app developers to simplify a variety of concurrent and asynchronous tasks. As it supports both Java and Kotlin, mobile app developers can use RxJava regardless of their choice of official programming language for Android. They can even extend RxJava by integrating it with a number of external libraries. RxJava 2.x further simplifies Android app development by supporting several new static, instance, abstract, and concrete methods.

What is RxJava? Understanding Important Aspects of RxJava

A Lightweight Implementation of ReactiveX

As noted earlier, RxJava is an open source implementation of ReactiveX library for JVM. By design, RxJava is a simple and lightweight implementation. Developers implement as a single JAR file. But it still enables programmers to orchestrate multiple actions simultaneously and smoothly without using call backs or global state management. The developers can use RxJava to orchestrate a variety of actions triggered due to specific events in the system efficiently.

Supports Several JVM-Based Programming Languages

In addition to being designed as a lightweight API, RxJava supports several widely used JVM-based programming languages. It even supports the two official programming languages for Android app development – Java and Kotlin. At present,Android app developers use RxJava widely to perform various asynchronous and concurrent tasks more efficiently. The Android app developers can further use RxJava to accelerate development of both simple and complex mobile apps.

Provides Two Major Classes

RxJava simplifies current and asynchronous task execution by providing two major classes – Observable and Subscriber. The Observable class emits the stream of events or data which are processed or handled by the Subscriber class. The Observable emits multiple items consistently. A single Observable can further mange these emitted items efficiently through multiple Subscribers. Each time the observable emits an item, RxJava sends it to Subscriber.onNext method for handling. After emitting an item, Observable calls the Subscriber.onComplete method. In case there is an error, Observable will call the Subscriber.onError method.

Implements Stream Abstracts through Three Core Constructs

RxJava requires Android app developers to treat everything – click event, push notification, location update – as stream. It even implements the stream abstractions through three important components – observable, observer and operator. The observable emits various items as streams. The items emitted by observables are consumed by the observer. At the same time, operators filter, modify, or alter the items emitted by observables before they are consumed by the observer. RxJava even allows programmers to apply a number of commonly used functional programming operators to the observable stream.

Simplifies Multithreading through Schedulers

RxJava complements the observables, observers, and operators with another major component – schedulers. The operators can use schedulers as a thread-pool to manage and control the threads. Developers can also use schedulers for controlling the thread within which various operations take place in the observable chain. RxJava allows developers to operate the observable chain on single thread by not providing a scheduler. But the programmers must take advantage of scheduler to schedule operations which occurs sequentially. RxJava even allows developers to specify subscribers through multiple methods.

Compatible with Several Third-Party Libraries

The Java programmers can integrate RxJava seamlessly with a number of external libraries. For instance, they can reuse various Apache Camel components, protocols, and data formats by integrating RxJava API with Camel RX. Likewise, they can follow logs over HTTP by integrating RxJava API with rxjava-http-tail. Hence, it becomes easier for developers to extend RxJava according to the complex project needs. They can further accelerate Android app development by integrating RxJava with Android Studio.

Simplifies Android App Development

RxJava makes it easier for developers to orchestrate various actions and handle asynchronous data efficiently which writing an Android app in Java or Kotlin. It even performs various actions in the background, while allowing the app to react to user interactions. The developers can even take advantage of various functional programming concepts to handle the asynchronous data in an Android app in a simple and flexible way. Also, the developers can represent common events or actions as asynchronous data stream. They can manage the asynchronous data streams efficiently through the observable and subscriber classes.

On the whole, RxJava is an open source and lightweight implementation of ReactiveX library that supports a number of widely used JVM-based programming languages including Java and Kotlin. It is currently used widely by Android developers to perform various concurrent and asynchronous tasks efficiently while writing Android apps in Java or Kotlin. Also, RxJava has been evolving consistently to simplify composition of event-based and asynchronous programs.