Java Streams - Stream mapToDouble (ToDoubleFunction mapper)

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Stream mapToDouble(ToDoubleFunction<? super T> mapper) returns a DoubleStream consisting of the results of applying the given function to the elements of this stream.

Syntax

mapToDouble has the following syntax.

DoubleStream mapToDouble(ToDoubleFunction<? super T> mapper)

Example

The following example shows how to use mapToDouble.

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

    stringList.stream()
           .mapToDouble(n-> Double.parseDouble(n) )
           .filter(n-> n%2 == 0)
           .forEach(System.out::println);
  }
}

The code above generates the following result.

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