Generate lists from a list

freitas :

I've been searching around and I couldnt find a smart way of doing a split of a list.

Let's say we have the following example:

public class Person {
    private String name;
    private int age;
    private String gender;

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

    // Getters/setters
}

So then I have:

List<Person> personList = new ArrayList<>();
personList.add(new Person("Adam", 30, "male"));
personList.add(new Person("John", 32, "male"));
personList.add(new Person("Monica", 30, "female"));
personList.add(new Person("Sophia", 20, "female"));
personList.add(new Person("Carol", 25, "female"));

Is there a way that I could generate two new lists of Person using Stream API grouping male and female?

J.Adler :

Sorry for the brevity, but I'm on the train going home.

Map<String, List<Person>> map = list.stream()
    .collect(Collectors.groupingBy(Person::getGender));

And the code

public class Person {
    private String name;
    private int age;
    private String genre;

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

    // getters and setters
}

public class GroupBy {

    public static void main(String[] args) {

        List<Person> list = ArrayList();

        liist.add(new Person("Adam", 30, male));
        list.add(new Person("John", 32, male));
        list.add(new Person("Monica", 30, female));
        list.add(new Person("Sophia", 20, female));
        list.add(new Person("Carol", 25, female));

        Map<String, List<Person>> map = list.stream()
            .collect(Collectors.groupingBy(Person::getGender));
    }
}