Module java.base
Package java.util.concurrent

Interface Flow.Publisher<T>

Type Parameters:
T - the published item type
All Known Subinterfaces:
Flow.Processor<T,​R>, HttpRequest.BodyPublisher
All Known Implementing Classes:
SubmissionPublisher
Enclosing class:
Flow
Functional Interface:
This is a functional interface and can therefore be used as the assignment target for a lambda expression or method reference.
@FunctionalInterface
public static interface Flow.Publisher<T>
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.

  • Method Summary

    Modifier and Type Method Description
    void subscribe​(Flow.Subscriber<? super T> subscriber)
    Adds the given Subscriber if possible.

  • Method Details

    • subscribe

      void subscribe​(Flow.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