PublishSubject caches error, won't emit onNext

Not sure if this is intended behavior, but when using a PublishSubject (and any other subject) the error seems to be cached, so each time I subscribe to the subject it propagates that error again. Additionally, subsequent calls to onNext are ignored.

PublishSubject<String> subject = PublishSubject.create();
subject.onError(new RuntimeException());
subject.subscribe(
        System.out::println,
        System.err::println
);
subject.onNext("Hello World!"); // never emitted

If this is intended behavior, how would I go about implementing something that emits errors but will continue normally afterwards?

I’ve resolved in the mean time to using two subjects: one that emits the onNext, one that emits the onError:

PublishSubject<String> successSubject = PublishSubject.create();
PublishSubject<Throwable> errorSubject = PublishSubject.create();
observable.subscribe(
    successSubject::onNext,
    errorSubject::onNext
);

[jrobinson3k1]

@akarnokd doing that doesn’t seem much better, since now your type parameter would need to be Object rather than the expected type. It’s a murky solution either way. What would be nice is a way to reset an Observable after it has been terminated, either by onComplete or onError, by just putting it back in its initial state, but keep its subscribers. This can be done manually, but an Rx solution would be handy.

It sounds like this flies in the face of the designed contracts, though.

[richardtop]

@akarnokd thanks for the comment, I’ve actually using RxSwift and was comparing the Rx interface with more usual Promises or Futures interfaces. They look a bit nicer at the call site, as I may want just propagate the error further, but handle Success a bit differently.