How to ignore error and continue infinite stream?

Ziem picture Ziem · Mar 10, 2015 · Viewed 43.8k times · Source

I would like to know how to ignore exceptions and continue infinite stream (in my case stream of locations)?

I'm fetching current user position (using Android-ReactiveLocation) and then sending them to my API (using Retrofit).

In my case, when exception occurs during network call (e.g. timeout) onError method is invoked and stream stops itself. How to avoid it?

Activity:

private RestService mRestService;
private Subscription mSubscription;
private LocationRequest mLocationRequest = LocationRequest.create()
            .setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY)
            .setInterval(100);
...
private void start() {
    mRestService = ...;
    ReactiveLocationProvider reactiveLocationProvider = new ReactiveLocationProvider(this);
    mSubscription = reactiveLocationProvider.getUpdatedLocation(mLocationRequest)
            .buffer(50)
            .flatMap(locations -> mRestService.postLocations(locations)) // can throw exception
            .subscribeOn(Schedulers.newThread())
            .observeOn(AndroidSchedulers.mainThread())
            .subscribe();
}

RestService:

public interface RestService {
    @POST("/.../")
    Observable<Response> postLocations(@Body List<Location> locations);
}

Answer

tomrozb picture tomrozb · Mar 10, 2015

You may want to use one of the error handling operators.

  • onErrorResumeNext( ) — instructs an Observable to emit a sequence of items if it encounters an error
  • onErrorReturn( ) — instructs an Observable to emit a particular item when it encounters an error
  • onExceptionResumeNext( ) — instructs an Observable to continue emitting items after it encounters an exception (but not another variety of throwable)
  • retry( ) — if a source Observable emits an error, resubscribe to it in the hopes that it will complete without error
  • retryWhen( ) — if a source Observable emits an error, pass that error to another Observable to determine whether to resubscribe to the source

Especialy retry and onExceptionResumeNext look promising in your case.