io.reactivex.observable

Interface Observer<T>

Type Parameters:

T - the type of item the Observer expects to observe

All Known Implementing Classes:

AsyncSubject, BehaviorSubject, DefaultObserver, DisposableObserver, PublishSubject, ReplaySubject, ResourceObserver, SafeObserver, SerializedObserver, Subject, TestObserver, UnicastSubject

public interface Observer<T>

Provides a mechanism for receiving push-based notifications.

After an Observer calls an Observable's subscribe method, first the Observable calls onSubscribe(Disposable) with a Disposable that allows cancelling the sequence at any time, then the Observable may call the Observer's onNext(T) method any number of times to provide notifications. A well-behaved Observable will call an Observer's onComplete() method exactly once or the Observer's onError(java.lang.Throwable) method exactly once.

See Also:

ReactiveX documentation: Observable

Method Summary

Modifier and Type	Method and Description
void	onComplete() Notifies the Observer that the Observable has finished sending push-based notifications.
void	onError(java.lang.Throwable e) Notifies the Observer that the Observable has experienced an error condition.
void	onNext(T t) Provides the Observer with a new item to observe.
void	onSubscribe(io.reactivex.common.Disposable d) Provides the Observer with the means of cancelling (disposing) the connection (channel) with the Observable in both synchronous (from within onNext(Object)) and asynchronous manner.

Method Detail

onSubscribe

void onSubscribe(@NonNull
                 io.reactivex.common.Disposable d)

Provides the Observer with the means of cancelling (disposing) the connection (channel) with the Observable in both synchronous (from within onNext(Object)) and asynchronous manner.

Parameters:

d - the Disposable instance whose Disposable.dispose() can be called anytime to cancel the connection

Since:

2.0

onNext

void onNext(@NonNull
            T t)

Provides the Observer with a new item to observe.

The Observable may call this method 0 or more times.

The Observable will not call this method again after it calls either onComplete() or onError(java.lang.Throwable).

Parameters:

t - the item emitted by the Observable

onError

void onError(@NonNull
             java.lang.Throwable e)

Notifies the Observer that the Observable has experienced an error condition.

If the Observable calls this method, it will not thereafter call onNext(T) or onComplete().

Parameters:

e - the exception encountered by the Observable

onComplete

void onComplete()

Notifies the Observer that the Observable has finished sending push-based notifications.

The Observable will not call this method if it calls onError(java.lang.Throwable).