HashMap to List (java)

hashmap-to-list.java

import java.util.*;

public class HashMapToList {
    public static void main(String[] args) {
        HashMapToList hashMapToList = new HashMapToList();
        hashMapToList.init();
    }

    private void init() {
        List<User> users = toList(getData());
        System.out.println(users);
    }

    private Map<User, List<User>> getData() {
        Map<User, List<User>> data = new HashMap<>();

        User kushina = new User(10, "Kushina", null );
        User naruto = new User(11, "Naruto", 10 );
        data.put(kushina, Arrays.asList(naruto));


        User sangeetha = new User(20, "Sangeetha", null );
        User sanjay = new User(21, "Sanjay Vijay", 20 );
        User divya = new User(22, "Divya Saasha Vijay", 20 );
        data.put(sangeetha, Arrays.asList(sanjay, divya));

        User jyothika = new User(30, "Jyothika", null );
        User diya = new User(31, "Diya Suriya", 30 );
        User dev = new User(31, "Dev Suriya", 30 );
        data.put(jyothika, Arrays.asList(dev, diya));

        return data;
    }

    private List<User> toList(Map<User, List<User>> usersMap) {
        List<User> users = new ArrayList<>();

        usersMap.entrySet().stream().forEach(entry -> {
            User parent = entry.getKey();
            List<User> children = entry.getValue();

            children.stream().forEach(child -> {
                child.setParentName(parent.getName());
                users.add(child);
            });
        });

        return users;
    }
}


class User {
    int id;
    String name;
    Integer parentId;
    String parentName;

    public User(int id, String name, Integer parentId) {
        this.id = id;
        this.name = name;
        this.parentId = parentId;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Integer getParentId() {
        return parentId;
    }

    public void setParentId(Integer parentId) {
        this.parentId = parentId;
    }

    public String getParentName() {
        return parentName;
    }

    public void setParentName(String parentName) {
        this.parentName = parentName;
    }
}