Main.java Source code

Introduction

Here is the source code for Main.java

Source

import java.util.Arrays;
import java.util.List;
import java.util.Map;
import java.util.stream.Collectors;

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));

        Map<Integer, List<Person>> personsByAge = persons.stream().collect(Collectors.groupingBy(p -> p.age));

        personsByAge.forEach((age, p) -> System.out.format("age %s: %s\n", age, p));
    }

}

class Person {
    String name;
    int age;

    Person(String name, int age) {
        this.name = name;
        this.age = age;
    }

    @Override
    public String toString() {
        return name;
    }
}