Java Streams - Stream flatMap(Function mapper) example

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Stream flatMap(Function<? super T,? extends Stream<? extends R>> mapper) returns a stream by replacing this stream with a mapped stream by applying the provided mapping function.

Syntax

flatMap has the following syntax.

<R> Stream<R> flatMap(Function<? super T,? extends Stream<? extends R>> mapper)

Example

The following example shows how to use flatMap.

import java.util.Arrays;
import java.util.List;
import java.util.stream.Stream;
//  w w  w  .j a v  a  2s  .  c o m
public class Main {
  public static void main(String[] args) {
    List<String> stringList = Arrays.asList("1.2","2.2","3","4","5");

    stringList.stream()
           .flatMap(n-> Stream.of(n) )
           .forEach(System.out::println);
  }
}

The code above generates the following result.

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