plugins.markdown

layout	title	id
documentation	ReactiveX - Plugins	plugins

#Plugins

Plugins allow you to modify the default behavior of RxJava in several respects:

• by changing the set of default computation, i/o, and new thread Schedulers
• by registering a handler for extraordinary errors that RxJava may encounter
• by registering functions that can take note of the occurrence of several regular RxJava activities

RxJavaDefaultSchedulers

This plugin allows you to override the default computation, i/o, and new thread Schedulers with Schedulers of your choosing. To do this, extend the class RxJavaDefaultSchedulers and override these methods:

• Scheduler getComputationScheduler( )
• Scheduler getIOScheduler( )
• Scheduler getNewThreadScheduler( )

Then follow these steps:

1. Create an object of the new RxJavaDefaultSchedulers subclass you have implemented.
2. Obtain the global RxJavaPlugins instance via RxJavaPlugins.getInstance( ).
3. Pass your default schedulers object to the registerDefaultSchedulers( ) method of that instance.

When you do this, RxJava will begin to use the Schedulers returned by your methods rather than its built-in defaults.

RxJavaErrorHandler

This plugin allows you to register a function that will handle errors that are raised by RxJava but that cannot be handled by the ordinary RxJava onError notification process (for instance, if RxJava tries to propagate an error to a subscriber that has not implemented an onError handler). To do this, extend the class RxJavaErrorHandler and override this method:

• void handleError(Throwable e)

Then follow these steps:

1. Create an object of the new RxJavaErrorHandler subclass you have implemented.
2. Obtain the global RxJavaPlugins instance via RxJavaPlugins.getInstance( ).
3. Pass your error handler object to the registerErrorHandler( ) method of that instance.

When you do this, RxJava will begin to use your error handler to field errors that cannot be handled in ordinary ways.

RxJavaObservableExecutionHook

This plugin allows you to register functions that RxJava will call upon certain regular RxJava activities, for instance for logging or metrics-collection purposes. To do this, extend the class RxJavaObservableExecutionHook and override any or all of these methods:

method	when invoked
onCreate( )	during Observable.create( )
onSubscribeStart( )	immediately before Observable.subscribe( )
onSubscribeReturn( )	immediately after Observable.subscribe( )
onSubscribeError( )	upon a failed execution of Observable.subscribe( )
onLift( )	during Observable.lift( )

Then follow these steps:

1. Create an object of the new RxJavaObservableExecutionHook subclass you have implemented.
2. Obtain the global RxJavaPlugins instance via RxJavaPlugins.getInstance( ).
3. Pass your execution hooks object to the registerObservableExecutionHook( ) method of that instance.

When you do this, RxJava will begin to call your functions when it encounters the specific conditions they were designed to take note of.