Package com.mongodb.async.client

Interface Observer<TResult>

Type Parameters:

TResult - The type of element signaled.

public interface Observer<TResult>

Provides a mechanism for receiving push-based notifications.

Will receive a call to onSubscribe(Subscription) on subscription to the Observable. No further notifications will be received until Subscription.request(long) is called.

After signaling demand:

• One or more invocations of onNext(Object) up to the maximum number defined by Subscription.request(long)
• Single invocation of onError(Throwable) or onComplete() which signals a terminal state after which no further events will be sent.

Demand can be signaled via Subscription.request(long) whenever the Observer instance is capable of handling more.

Since:

3.1

Method Summary

Modifier and Type	Method	Description
void	onComplete()	Notifies the Subscriber that the Observable has finished sending push-based notifications.
void	onError(Throwable e)	Notifies the Observer that the Observable has experienced an error condition.
void	onNext(TResult result)	Provides the Observer with a new item to observe.
void	onSubscribe(Subscription subscription)	Invoked on subscription to an Observable.

Method Detail

onSubscribe

void onSubscribe(Subscription subscription)

Invoked on subscription to an Observable.

No operation will happen until Subscription.request(long) is invoked.

It is the responsibility of this Subscriber instance to call Subscription.request(long) whenever more data is wanted.

The MongoIterable will send notifications only in response to Subscription.request(long).

Parameters:

subscription - Subscription that allows requesting data via Subscription.request(long)

onNext

void onNext(TResult result)

Provides the Observer with a new item to observe.

The Observer 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:

result - the item emitted by the Observable

onError

void onError(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(TResult) or onComplete().

Parameters:

e - the exception encountered by the Observable

onComplete

void onComplete()

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

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