zipWithIndex

Zips elements of current flow with its indices.

Signature

def zipWithIndex: Repr[(Out, Long)]

Description

Zips elements of current flow with its indices.

emits upstream emits an element and is paired with their index

backpressures when downstream backpressures

completes when upstream completes

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.Source;
import akka.stream.javadsl.Sink;
import java.util.Arrays;

Source.from(Arrays.asList("apple", "orange", "banana"))
    .zipWithIndex()
    .runWith(Sink.foreach(System.out::print), materializer);
// this will print ('apple', 0), ('orange', 1), ('banana', 2)