public Interface ObservableEmitter<T>

The onNext(Object), onError(Throwable), tryOnError(Throwable) and onComplete() methods should be called in a sequential manner, just like the Observer's methods should be. Use the ObservableEmitter the serialize() method returns instead of the original ObservableEmitter instance provided by the generator routine if you want to ensure this. The other methods are thread-safe.

The emitter allows the registration of a single resource, in the form of a Disposable or Cancellable via setDisposable(Disposable) or setCancellable(Cancellable) respectively. The emitter implementations will dispose/cancel this instance when the downstream cancels the flow or after the event generator logic calls onError(Throwable), onComplete() or when tryOnError(Throwable) succeeds.

Only one Disposable or Cancellable object can be associated with the emitter at a time. Calling either set method will dispose/cancel any previous object. If there is a need for handling multiple resources, one can create a io.reactivex.disposables.CompositeDisposable and associate that with the emitter instead.

The Cancellable is logically equivalent to Disposable but allows using cleanup logic that can throw a checked exception (such as many close() methods on Java IO components). Since the release of resources happens after the terminal events have been delivered or the sequence gets cancelled, exceptions throw within Cancellable are routed to the global error handler via io.reactivex.plugins.RxJavaPlugins#onError(Throwable).