如何在java中对List<HashMap<String，String>> ls进行排序？

import java.util.*;

public class Main {
    public static void main(String[] args) {
        List<HashMap<String, String>> ls = new ArrayList<>();

        HashMap<String, String> map1 = new HashMap<>();
        map1.put("name", "John");
        map1.put("age", "25");
        ls.add(map1);

        HashMap<String, String> map2 = new HashMap<>();
        map2.put("name", "Alice");
        map2.put("age", "30");
        ls.add(map2);

        HashMap<String, String> map3 = new HashMap<>();
        map3.put("name", "Bob");
        map3.put("age", "20");
        ls.add(map3);

        // 使用Comparator接口实现排序
        Collections.sort(ls, new Comparator<HashMap<String, String>>() {
            @Override
            public int compare(HashMap<String, String> o1, HashMap<String, String> o2) {
                // 根据name字段进行排序
                return o1.get("name").compareTo(o2.get("name"));
            }
        });

        // 输出排序结果
        for (HashMap<String, String> map : ls) {
            System.out.println(map.get("name") + " " + map.get("age"));
        }
    }
}