RxJava
ReactiveX is an API for asynchronous programming with observable streams, which is a combination of the best ideas from the Observer pattern, the Iterator pattern, and functional programming.
RxJava is a Java VM implementation of Reactive Extensions. It extends the observer pattern to support sequences of data/events and adds operators that allow you to compose sequences together declaratively while abstracting away concerns about things like low-level threading, synchronization, thread-safety and concurrent data structures.
RxJava tries to be very lightweight. It is implemented as a single JAR that is focused on just the Observable abstraction and related higher-order functions. And the JAR can be downloaded here.
RxJava Junior
There are plenty of good resources of RxJava and RxAndroid recently, including articles, blogs, githubs and books. As for articles, the best ones for the beginners will be The introduction to Reactive Programming you've been missing and Details of RxJava for Android developers. For blogs, the RxWeekend and Daniel Lew is awesome. And for githubs, there is a collection of Awesome RxJava resources. Also, there is a book available called RxJava Essentials. Last but not least, the RxJava wiki should not be ignored.
RxJava Intermediate
When you are familiar with the concepts and codes of RxJava, you can start to inspect the formation of RxJava API, all kinds of RxJava operators and so on. For the RxJava API, the java doc is a good way to start. And RxMarbles is a website to show you what those operators do mean interactively.
RxJava Senior
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RxJava Example
There is a github repo RxMobile to demonstrate the power of RxJava brings to Android platform, using douban API.
