当值为对象时，按属性对hashMap进行排序

import java.util.*;

public class HashMapSortingExample {
    public static void main(String[] args) {
        // 创建一个HashMap并添加对象
        HashMap<Integer, Person> hashMap = new HashMap<>();
        hashMap.put(1, new Person("John", 25));
        hashMap.put(2, new Person("Alice", 30));
        hashMap.put(3, new Person("Bob", 20));

        // 将HashMap中的对象按照年龄属性进行排序
        List<Map.Entry<Integer, Person>> list = new ArrayList<>(hashMap.entrySet());
        Collections.sort(list, new Comparator<Map.Entry<Integer, Person>>() {
            @Override
            public int compare(Map.Entry<Integer, Person> o1, Map.Entry<Integer, Person> o2) {
                return o1.getValue().getAge() - o2.getValue().getAge();
            }
        });

        // 打印排序后的结果
        for (Map.Entry<Integer, Person> entry : list) {
            System.out.println("Key: " + entry.getKey() + ", Value: " + entry.getValue());
        }
    }
}

class Person {
    private String name;
    private int age;

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

    public String getName() {
        return name;
    }

    public int getAge() {
        return age;
    }

    @Override
    public String toString() {
        return "Person{" +
                "name='" + name + '\'' +
                ", age=" + age +
                '}';
    }
}