RxAndroid

The previous sections cover all the main topic of RxJava. This sections will go a step further, introducing some additional features that bring RxJava to the Android ecosystem.

RxAndroid is a separate module of RxJava, that gives some useful bindings to the developer.

The AndroidSchedulers package provides some specific scheduler for the Android threading system.

The additional schedulers provided are:

• AndroidSchedulers.mainThread( ), that will execute an action on the main Android UI thread
• AndroidSchedulers.handlerThread(Handler handler), that uses the provided Handler to execute an action

A typical example of the usage of mainThread( ) is the following, that performs a download in the scheduler io( ) and the show the image to the user:

service.getImage(url)
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.subscribe(bitmap -> myImageView.setImageBitmap(bitmap));

ViewObservable is another feature that adds some bindings for android View that returns observables of events that come from the UI, such as:

• clicks( ), that emits a new item each time a View is clicked
• text( ), that emits a new item each time a TextView's text content is changed
• input( ), same as above, for CompoundButtons
• itemClicks( ), same as above, for AdapterViews

These methods are useful to bind the events from the user of an application, reifying its action and reacting with some operation, in a declarative way.