Migrating from RxJava 1.0 to RxJava 2.0 and Learn RxJava by Examples


This article will help you learn RxJava 2.0 by example. It will also show you how to migrate from RxJava 1.0.

If you are just getting starting with RxJava, here’s a sample project to learn it with examples. You can dive right in, build the project, and start learning:

Check out Fast Android Networking Library which supports RxJava2.

RxJava 2.0 has been completely rewritten from scratch on top of the Reactive-Streams specification. This specification itself has evolved out of RxJava 1.x, and provides a common baseline for reactive systems and libraries.

Because Reactive-Streams has a different architecture, it mandates changes to some well known RxJava types.

Here’s what’s changed from RxJava 1.0:

  • onCompleted became onComplete — without the trailing d
  • Func1 became Function
  • Func2 became BiFunction
  • CompositeSubscription became CompositeDisposable
  • limit operator has been removed. Use take in RxJava 2.

If you look at this project, you’ll find the following:

  • An example using CompositeDisposable, since CompositeSubscription and Subscription have been removed.
  • An example using Flowable.
  • An example using SingleObserver and CompletableObserver.
  • An example using RxJava2 operators such as map, zip, take, reduce, flatMap, filter, buffer, and much more.
  • An example using Function since Func1 has been removed.
  • An example using BiFunction since Func2 has been removed.
  • And many others examples.

Here are a few important RxJava operators that are covered in the project, and what they do:

  • Map transforms the items emitted by an Observable by applying a function to each item
  • Zip combines the emissions of multiple Observables together via a specified function, then emits a single item for each combination based on the results of this function
  • Filter emits only those items from an Observable that pass a predicate test
  • FlatMap transforms the items emitted by an Observable into Observables, then flattens the emissions from those into a single Observable
  • Take emits only the first n items emitted by an Observable
  • Reduce applies a function to each item emitted by an Observable, sequentially, and emits the final value
  • Skip suppresses the first n items emitted by an Observable
  • Buffer periodically gathers items emitted by an Observable into bundles and emits these bundles rather than emitting the items one at a time
  • Concat emits the emissions from two or more Observables without interleaving them
  • Replay ensures that all observers see the same sequence of emitted items, even if they subscribe after the Observable has begun emitting items
  • Merge combines multiple Observables into one by merging their emissions

Complete RxJava Tutorial

RxJava is a Java VM implementation of Reactive Extensions. It has become the single most important skill for Android development.

Just login here and learn RxJava.

Happy Coding 🙂

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Amit Shekhar

Amit Shekhar

Co-Founder at Mindorks | Learning is a journey, let’s learn together