Gatherer.Downstream (Java SE 25 & JDK 25)
Description: declaration: module: java.base, package: java.util.stream, interface: Gatherer, interface: Downstream
Keywords: java.util.stream.Gatherer.Downstream interface

# Interface Gatherer.Downstream<T>

Type Parameters:
  `T` - the type of elements this downstream accepts

Enclosing interface:
  `Gatherer<T,A,R>`

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 Gatherer.Downstream<T>
A Downstream object is the next stage in a pipeline of operations, to which elements can be sent.

Since:
  24

- ## Method Summary

  Modifier and Type
  Method
  Description
  `default boolean`
  `isRejecting()`
  Checks whether the next stage is known to not want any more elements sent to it.
  `boolean`
  `push(T element)`
  Pushes, if possible, the provided element downstream -- to the next stage in the pipeline.

- ## Method Details

  - ### push

    boolean push(T element)
    Pushes, if possible, the provided element downstream -- to the next stage in the pipeline.
    Implementation Requirements:
      If this method returns `false` then no further elements will be accepted and subsequent invocations of this method will return `false`.
    Parameters:
      `element` - the element to push downstream
    Returns:
      `true` if more elements can be sent, and `false` if not.

  - ### isRejecting

    default boolean isRejecting()
    Checks whether the next stage is known to not want any more elements sent to it.
    API Note:
      This is best-effort only, once this returns `true` it should never return `false` again for the same instance.
    Implementation Requirements:
      The implementation in this interface returns `false`.
    Returns:
      `true` if this Downstream is known not to want any more elements sent to it, `false` if otherwise