Stream.Builder

AI-generated Key Takeaways

• Stream.Builder allows the creation of a Stream by adding elements individually, avoiding the overhead of using temporary buffers.

• The builder has two phases: a building phase where elements can be added and a built phase (triggered by build()) where the stream is created and no more elements can be added.

• accept(T t) and add(T t) methods are used to add elements to the stream during the building phase.

• build() method creates the Stream from the added elements and transitions the builder to the built state, preventing further modifications.

public static interface Stream.Builder implements Consumer<T>

A mutable builder for a Stream. This allows the creation of a Stream by generating elements individually and adding them to the Builder (without the copying overhead that comes from using an ArrayList as a temporary buffer.)

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 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.

See Also

• Stream.builder()

Public Method Summary

abstract void	accept(T t) Adds an element to the stream being built.
Builder<T>	add(T t) Adds an element to the stream being built.
abstract Stream<T>	build() Builds the stream, transitioning this builder to the built state.

Inherited Method Summary

From interface java.util.function.Consumer

abstract void	accept(T t) Performs this operation on the given argument.
Consumer<T>	andThen(Consumer<? super T> after) Returns a composed Consumer that performs, in sequence, this operation followed by the after operation.

Public Methods

public abstract void accept (T t)

Adds an element to the stream being built.

Parameters

t	the input argument

Throws

IllegalStateException	if the builder has already transitioned to the built state

public Builder<T> add (T t)

Adds an element to the stream being built.

Parameters

t	the element to add

Returns

• this builder

Throws

IllegalStateException	if the builder has already transitioned to the built state

public abstract Stream<T> 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