Flow.Subscriber

  • Flow.Subscriber is an interface defining a receiver of messages in a reactive stream.

  • It has four key methods: onSubscribe, onNext, onError, and onComplete, invoked sequentially for each subscription.

  • onSubscribe is called first to establish the subscription, enabling the subscriber to request items.

  • onNext delivers the next item in the stream, while onError signals an unrecoverable error, halting further delivery.

  • onComplete indicates the successful completion of the stream, signifying no more items will be delivered.
public static interface Flow.Subscriber
Known Indirect Subclasses

A receiver of messages. The methods in this interface are invoked in strict sequential order for each Flow.Subscription.

Public Method Summary

abstract void
onComplete()
Method invoked when it is known that no additional Subscriber method invocations will occur for a Subscription that is not already terminated by error, after which no other Subscriber methods are invoked by the Subscription.
abstract void
onError(Throwable throwable)
Method invoked upon an unrecoverable error encountered by a Publisher or Subscription, after which no other Subscriber methods are invoked by the Subscription.
abstract void
onNext(T item)
Method invoked with a Subscription's next item.
abstract void
onSubscribe(Flow.Subscription subscription)
Method invoked prior to invoking any other Subscriber methods for the given Subscription.

Public Methods

public abstract void onComplete ()

Method invoked when it is known that no additional Subscriber method invocations will occur for a Subscription that is not already terminated by error, after which no other Subscriber methods are invoked by the Subscription. If this method throws an exception, resulting behavior is undefined.

public abstract void onError (Throwable throwable)

Method invoked upon an unrecoverable error encountered by a Publisher or Subscription, after which no other Subscriber methods are invoked by the Subscription. If this method itself throws an exception, resulting behavior is undefined.

Parameters
throwable the exception

public abstract void onNext (T item)

Method invoked with a Subscription's next item. If this method throws an exception, resulting behavior is not guaranteed, but may cause the Subscription to be cancelled.

Parameters
item the item

public abstract void onSubscribe (Flow.Subscription subscription)

Method invoked prior to invoking any other Subscriber methods for the given Subscription. If this method throws an exception, resulting behavior is not guaranteed, but may cause the Subscription not to be established or to be cancelled.

Typically, implementations of this method invoke subscription.request to enable receiving items.

Parameters
subscription a new subscription