Learning RxJava

Observable.error()

This too is something you likely will only do with testing, but you can create an Observable that immediately calls onError() with a specified exception:

    import io.reactivex.Observable;    public class Launcher {      public static void main(String[] args) {                Observable.error(new Exception("Crash and burn!"))          .subscribe(i -> System.out.println("RECEIVED: " + i),            Throwable::printStackTrace,              () ->  System.out.println("Done!"));      }     }

The output is as follows:

    java.lang.Exception: Crash and burn!    at Launcher.lambda$main$0(Launcher.java:7)    at io.reactivex.internal.operators.observable.      ObservableError.subscribeActual(ObservableError.java:32)    at io.reactivex.Observable.subscribe(Observable.java:10514) at io.reactivex.Observable.subscribe(Observable.java:10500) ...