zipWithIndex

Zips elements of current flow with its indices.

Fan-in operators

Signature

Source.zipWithIndexSource.zipWithIndex Flow.zipWithIndexFlow.zipWithIndex

Description

Zips elements of current flow with its indices.

See also:

Example

Scala
sourceimport akka.stream.scaladsl.Source
import akka.stream.scaladsl.Sink

    Source(List("apple", "orange", "banana")).zipWithIndex.runWith(Sink.foreach(println))
    // this will print ('apple', 0), ('orange', 1), ('banana', 2)
Java
sourceimport akka.stream.javadsl.Keep;
import akka.stream.javadsl.Source;
import akka.stream.javadsl.Sink;

import java.util.*;

Source.from(Arrays.asList("apple", "orange", "banana"))
    .zipWithIndex()
    .runForeach(System.out::println, system);
// this will print ('apple', 0), ('orange', 1), ('banana', 2)

Reactive Streams semantics

emits upstream emits an element and is paired with their index

backpressures when downstream backpressures

completes when upstream completes

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