I wrote this code to check the even numbers from the List. After finding even number I twice the even numbers with the help of Map and then find the sum of each even number after making it double by use of the reduce method.import java.util.Arrays;import java.util.List;public static void main(String[] args) {List<Integer> numbers = Arrays.asList(1, 2, 3, 4, 5, 6, 7, 8, 9);System.out.println(numbers.stream()        .filter(e -> e % 2 == 0)        .map( e -> e * 2)        .reduce(0, Integer::sum));}
Lambda expression to check even numbers
java;lambda
Have you come across the IntStream?  I'd use that for numerical operations rather than the boxed version Stream<Integer>.