LongStream.Builder (Java Platform SE 8 )
Keywords: java.util.stream.LongStream.Builder interface
Date: 2026-03-16

compact1, compact2, compact3
java.util.stream

## Interface LongStream.Builder

- All Superinterfaces:
    LongConsumer
  Enclosing interface:
    LongStream

      public static interface LongStream.Builder
      extends LongConsumer

  A mutable builder for a `LongStream`.

  A stream builder has a lifecycle, which starts in a building phase, during which elements can be added, and then transitions to a built phase, after which elements may not be added. The built phase begins begins when the `build()` method is called, which creates an ordered stream whose elements are the elements that were added to the stream builder, in the order they were added.

  Since:
    1.8
  See Also:
    `LongStream.builder()`

- - ### Method Summary

    All Methods Instance Methods Abstract Methods Default Methods
    Modifier and Type | Method and Description
    --- | ---
    `void` | `accept(long t)` Adds an element to the stream being built.
    `default LongStream.Builder` | `add(long t)` Adds an element to the stream being built.
    `LongStream` | `build()` Builds the stream, transitioning this builder to the built state.

    - ### Methods inherited from interface java.util.function.LongConsumer

      `andThen`

- - ### Method Detail

    - #### accept

          void accept(long t)

      Adds an element to the stream being built.
      Specified by:
        `accept` in interface `LongConsumer`
      Parameters:
        `t` - the input argument
      Throws:
        `IllegalStateException` - if the builder has already transitioned to the built state

    - #### add

          default LongStream.Builder add(long t)

      Adds an element to the stream being built.
      Implementation Requirements:
        The default implementation behaves as if:

                 accept(t)
                 return this;

      Parameters:
        `t` - the element to add
      Returns:
        `this` builder
      Throws:
        `IllegalStateException` - if the builder has already transitioned to the built state

    - #### build

          LongStream build()

      Builds the stream, transitioning this builder to the built state. An `IllegalStateException` is thrown if there are further attempts to operate on the builder after it has entered the built state.
      Returns:
        the built stream
      Throws:
        `IllegalStateException` - if the builder has already transitioned to the built state

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