Flow.Publisher

  • Flow.Publisher represents a producer of items received by Flow.Subscriber instances, delivering items in the same order to each subscriber.

  • If an error prevents item delivery, subscribers receive an onError signal, followed by no further messages; otherwise, they receive an onComplete signal when no more items are expected.

  • Publishers can differ in how they handle drops (e.g., resource limitations) and whether new subscribers receive previously produced items.

  • The subscribe method allows adding a subscriber, which can then request items and unsubscribe using the provided Flow.Subscription.

  • Subscribing with a null subscriber or facing policy violations during subscription results in an IllegalStateException or a NullPointerException, respectively, sent to the subscriber's onError method.
public static interface Flow.Publisher
Known Indirect Subclasses

A producer of items (and related control messages) received by Subscribers. Each current Flow.Subscriber receives the same items (via method onNext) in the same order, unless drops or errors are encountered. If a Publisher encounters an error that does not allow items to be issued to a Subscriber, that Subscriber receives onError, and then receives no further messages. Otherwise, when it is known that no further messages will be issued to it, a subscriber receives onComplete. Publishers ensure that Subscriber method invocations for each subscription are strictly ordered in happens-before order.

Publishers may vary in policy about whether drops (failures to issue an item because of resource limitations) are treated as unrecoverable errors. Publishers may also vary about whether Subscribers receive items that were produced or available before they subscribed.

Public Method Summary

abstract void
subscribe(Subscriber<? super T> subscriber)
Adds the given Subscriber if possible.

Public Methods

public abstract void subscribe (Subscriber<? super T> subscriber)

Adds the given Subscriber if possible. If already subscribed, or the attempt to subscribe fails due to policy violations or errors, the Subscriber's onError method is invoked with an IllegalStateException. Otherwise, the Subscriber's onSubscribe method is invoked with a new Flow.Subscription. Subscribers may enable receiving items by invoking the request method of this Subscription, and may unsubscribe by invoking its cancel method.

Parameters
subscriber the subscriber
Throws
NullPointerException if subscriber is null