根据计数对包含对象的ArrayList的哈希图进行排序

Question

我有一个包含名字和姓氏，年龄，电子邮件，性别，城市和州的字符串数组。我应该使用ArrayList和哈希映射来计算生活在每个州的人数，并按升序打印。这是我到目前为止的内容：

我使用ArrayList来创建对象并将其放入其中。在我的哈希图中，我需要为每个州都有一个密钥和数组列表，其中将包含居住在那里的用户

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;

public class MainPart1 {

public static void main(String[] args) {

    List<User> listOfUsers = new ArrayList<>();
    HashMap<String, ArrayList<User>> hmap = new HashMap<>();

    for (String str : Data.users) {
        String[] userData = str.split(",");
        User newUser = new User(userData[0], userData[1], Integer.parseInt(userData[2]), userData[3], userData[4], userData[5], userData[6]);
        listOfUsers.add(newUser);
    }

    for (String str : Data.otherUsers) {
        String[] userData = str.split(",");
        User newUser = new User(userData[0], userData[1], Integer.parseInt(userData[2]), userData[3], userData[4], userData[5], userData[6]);
        listOfUsers.add(newUser);
    }

    ArrayList<User> list;
    for (int i = 0; i < listOfUsers.size(); i++) {
        String key = listOfUsers.get(i).getState();
        if (hmap.containsKey(key)) {
            list = hmap.get(listOfUsers.get(i).getState());
        }

        else {
            list = new ArrayList<>();
        }

        list.add(listOfUsers.get(i));
        hmap.put(key, list);


    }

    System.out.println("State:       Count:");

    for (String key : hmap.keySet()) {
        System.out.print(key + "\t\t\t ");
        System.out.println(hmap.get(key).size());
    }

}

}

公共类用户{

private String firstName;
private String lastName;
private int age;
private String email;
private String gender;
private String city;
private String state;

public User(String firstName, String lastName, int age, String email, String gender, String city, String state) {
    this.firstName = firstName;
    this.lastName = lastName;
    this.age = age;
    this.email = email;
    this.gender = gender;
    this.city = city;
    this.state = state;
}

public String getFirstname() {
    return firstName;
}

public void setFirstname(String firstName) {
    this.firstName = firstName;
}

public String getLastName() {
    return lastName;
}

public void setLastName(String lastName) {
    this.lastName = lastName;
}

public int getAge() {
    return age;
}

public void setAge(int age) {
    this.age = age;
}

public String getEmail() {
    return email;
}

public void setEmail(String email) {
    this.email = email;
}

public String getGender() {
    return gender;
}

public void setGender(String gender) {
    this.gender = gender;
}

public String getCity() {
    return city;
}

public void setCity(String city) {
    this.city = city;
}

public String getState() {
    return state;
}

public void setState(String state) {
    this.state = state;
}

@Override
public String toString() {
    return firstName + "," + lastName + "," + age + "," + email + "," + gender + "," + city + "," + state;
}

}

我能够使用数组列表将对象放入哈希图中，但是我无法使其按升序工作