Package org.eclipse.microprofile.reactive.streams.operators

Interface TransformingOperators<T>

Type Parameters:
T - The type of the elements that this stream emits.
All Known Subinterfaces:
ProcessorBuilder<T,R>, PublisherBuilder<T>
public interface TransformingOperators<T>
Operations for transforming a stream.

The documentation for each operator uses marble diagrams to visualize how the operator functions. Each element flowing in and out of the stream is represented as a coloured marble that has a value, with the operator applying some transformation or some side effect, termination and error signals potentially being passed, and for operators that subscribe to the stream, an output value being redeemed at the end.

Below is an example diagram labelling all the parts of the stream.

Example marble diagram

  • Method Details

    • map

      <R> TransformingOperators<R> map(Function<? super T,? extends R> mapper)
      Map the elements emitted by this stream using the mapper function.

      map marbles diagram

      Type Parameters:
      R - The type of elements that the mapper function emits.
      Parameters:
      mapper - The function to use to map the elements.
      Returns:
      A new stream builder that emits the mapped elements.

    • flatMap

      <S> TransformingOperators<S> flatMap(Function<? super T,? extends PublisherBuilder<? extends S>> mapper)
      Map the elements to publishers, and flatten so that the elements emitted by publishers produced by the mapper function are emitted from this stream.

      flatMap marbles diagram

      This method operates on one publisher at a time. The result is a concatenation of elements emitted from all the publishers produced by the mapper function.

      Unlike flatMapRsPublisher(Function)}, the mapper function returns a org.eclipse.microprofile.reactive.streams type instead of an org.reactivestreams type.

      Type Parameters:
      S - The type of the elements emitted from the new stream.
      Parameters:
      mapper - The mapper function.
      Returns:
      A new stream builder.

    • flatMapRsPublisher

      <S> TransformingOperators<S> flatMapRsPublisher(Function<? super T,? extends org.reactivestreams.Publisher<? extends S>> mapper)
      Map the elements to publishers, and flatten so that the elements emitted by publishers produced by the mapper function are emitted from this stream.

      flatMapRsPublisher marble diagram

      This method operates on one publisher at a time. The result is a concatenation of elements emitted from all the publishers produced by the mapper function.

      Unlike flatMap(Function), the mapper function returns a org.eclipse.microprofile.reactive.streams builder instead of an org.reactivestreams type.

      Type Parameters:
      S - The type of the elements emitted from the new stream.
      Parameters:
      mapper - The mapper function.
      Returns:
      A new stream builder.

    • flatMapCompletionStage

      <S> TransformingOperators<S> flatMapCompletionStage(Function<? super T,? extends CompletionStage<? extends S>> mapper)
      Map the elements to CompletionStage, and flatten so that the elements the values redeemed by each CompletionStage are emitted from this stream. If the element is null, this operation should be failed with a NullPointerException.

      flatMapCompletionStage marble diagram

      This method only works with one element at a time. When an element is received, the mapper function is executed, and the next element is not consumed or passed to the mapper function until the previous CompletionStage is redeemed. Hence this method also guarantees that ordering of the stream is maintained.

      Type Parameters:
      S - The type of the elements emitted from the new stream.
      Parameters:
      mapper - The mapper function.
      Returns:
      A new stream builder.

    • flatMapIterable

      <S> TransformingOperators<S> flatMapIterable(Function<? super T,? extends Iterable<? extends S>> mapper)
      Map the elements to Iterable's, and flatten so that the elements contained in each iterable are emitted by this stream.

      flatMapIterable marble diagram

      This method operates on one iterable at a time. The result is a concatenation of elements contain in all the iterables returned by the mapper function.

      Type Parameters:
      S - The type of the elements emitted from the new stream.
      Parameters:
      mapper - The mapper function.
      Returns:
      A new stream builder.