io.reactivex.rxjava3.core

Interface ObservableEmitter<T>

Type Parameters:

T - the value type to emit

All Superinterfaces:

Emitter<T>

public interface ObservableEmitter<T>
extends Emitter<T>

Abstraction over an RxJava Observer that allows associating a resource with it.

The Emitter.onNext(Object), Emitter.onError(Throwable), tryOnError(Throwable) and Emitter.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 Emitter.onError(Throwable), Emitter.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 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 RxJavaPlugins.onError(Throwable).

Method Summary

Modifier and Type	Method and Description
boolean	isDisposed() Returns true if the downstream disposed the sequence or the emitter was terminated via Emitter.onError(Throwable), Emitter.onComplete() or a successful tryOnError(Throwable).
@NonNull ObservableEmitter<T>	serialize() Ensures that calls to onNext, onError and onComplete are properly serialized.
void	setCancellable(@Nullable Cancellable c) Sets a Cancellable on this emitter; any previous Disposable or Cancellable will be disposed/cancelled.
void	setDisposable(@Nullable Disposable d) Sets a Disposable on this emitter; any previous Disposable or Cancellable will be disposed/cancelled.
boolean	tryOnError(@NonNull Throwable t) Attempts to emit the specified Throwable error if the downstream hasn't cancelled the sequence or is otherwise terminated, returning false if the emission is not allowed to happen due to lifecycle restrictions.

Methods inherited from interface io.reactivex.rxjava3.core.Emitter

onComplete, onError, onNext

Method Detail

setDisposable

void setDisposable(@Nullable
                   @Nullable Disposable d)

Sets a Disposable on this emitter; any previous Disposable or Cancellable will be disposed/cancelled.

This method is thread-safe.

Parameters:

d - the Disposable, null is allowed

setCancellable

void setCancellable(@Nullable
                    @Nullable Cancellable c)

Sets a Cancellable on this emitter; any previous Disposable or Cancellable will be disposed/cancelled.

This method is thread-safe.

Parameters:

c - the Cancellable resource, null is allowed

isDisposed

boolean isDisposed()

Returns true if the downstream disposed the sequence or the emitter was terminated via Emitter.onError(Throwable), Emitter.onComplete() or a successful tryOnError(Throwable).

This method is thread-safe.

Returns:

true if the downstream disposed the sequence or the emitter was terminated

serialize

@NonNull
@NonNull ObservableEmitter<T> serialize()

Ensures that calls to onNext, onError and onComplete are properly serialized.

Returns:

the serialized ObservableEmitter

tryOnError

boolean tryOnError(@NonNull
                   @NonNull Throwable t)

Attempts to emit the specified Throwable error if the downstream hasn't cancelled the sequence or is otherwise terminated, returning false if the emission is not allowed to happen due to lifecycle restrictions.

Unlike Emitter.onError(Throwable), the RxjavaPlugins.onError is not called if the error could not be delivered.

History: 2.1.1 - experimental

Parameters:

t - the Throwable error to signal if possible

Returns:

true if successful, false if the downstream is not able to accept further events

Since:

2.2