reactivex/rxandroid

RxAndroid is a small extension library that connects RxJava, a popular Java library for handling asynchronous, event-driven programming, to Android's threading model. The core problem it solves is a very common one in Android development: you often need to do work on a background thread (fetching data from a network, reading from a database) and then update the user interface on the main thread. Android requires all UI updates to happen on the main thread, doing them from a background thread causes crashes. RxJava handles asynchronous work through a concept called Observables, streams of data or events that you can subscribe to and react to as results arrive. RxAndroid adds a Scheduler (essentially a thread dispatcher) called AndroidSchedulers.mainThread() that makes it simple to take the results of any background Observable and route them back to Android's main UI thread for safe display. The code example in the README shows this clearly: a sequence of values is processed on a new background thread, then results are delivered on the main thread by adding a single .observeOn(AndroidSchedulers.mainThread()) call. You can also route results to any arbitrary Android Looper (Android's message loop mechanism) using AndroidSchedulers.from(). Adding RxAndroid to an Android project requires two lines in the Gradle build file, the RxAndroid library itself plus the core RxJava library. The README recommends always depending explicitly on the latest RxJava version since RxAndroid releases are infrequent. The library is written in Java and licensed under Apache 2.0.