Java tutorial
import java.util.Arrays; import java.util.List; import java.util.stream.Stream; public class Main { public static void main(String[] args) { List<Integer> numbers = Arrays.asList(1, 2, 3, 4, 5); List<Integer> numbers1 = Arrays.asList(1, 2, 3, 4, 5); Stream<Integer> s = Stream.concat(numbers.stream(), numbers1.stream()); System.out.println(s.count()); } }