Java tutorial
import java.util.Arrays; import java.util.List; public class Main { public static void main(String[] args) throws Exception { List<Person> persons = Arrays.asList(new Person("Max", 18), new Person("Peter", 23), new Person("Pamela", 23), new Person("David", 12)); Person result = persons.stream().reduce(new Person("", 0), (p1, p2) -> { p1.age += p2.age; p1.name += p2.name; return p1; }); System.out.format("name=%s; age=%s", result.name, result.age); } } class Person { String name; int age; Person(String name, int age) { this.name = name; this.age = age; } @Override public String toString() { return name; } }