使用TreeSet对Map的值的元素进行排序

import java.util.Comparator;
import java.util.Map.Entry;
import java.util.Set;
import java.util.TreeMap;
class Student1{
    String name;
    int age;
    int score;

    public Student1(String name, int age, int score) {
        super();
        this.name = name;
        this.age = age;
        this.score = score;
    }

    @Override
    public String toString() {
        return "Student1 [name=" + name + ", age=" + age + ", score=" + score + "]";
    }


}
public class HashMapSortDemo {
    public static void main(String[] args) {
        TreeMap<String, Student1> hashmap = new TreeMap<>();
        Student1 s1 = new Student1("小明1",18,88);
        Student1 s2 = new Student1("小明2",13,28);
        Student1 s3 = new Student1("小明3",15,48);
        Student1 s4 = new Student1("小明4",17,558);
        Student1 s5 = new Student1("小明5",344,58);
        hashmap.put(s1.name, s1);
        hashmap.put(s2.name, s2);
        hashmap.put(s3.name, s3);
        hashmap.put(s4.name, s4);
        hashmap.put(s5.name, s5);
        TreeMap<String, Student1> sortMap = new TreeMap<>(new Comparator<String>() {
            //按照年龄排序
//          @Override
//          public int compare(String o1, String o2) {
//              int num = hashmap.get(o1).age - hashmap.get(o2).age;
//              return num;
//          }
            //按照成绩排序
            @Override
            public int compare(String o1, String o2) {
                int num = hashmap.get(o1).score - hashmap.get(o2).score;
                return num;
            }

        });
        sortMap.putAll(hashmap);
        Set<Entry<String,Student1>> entrySet = sortMap.entrySet();
        entrySet.forEach(c -> System.out.println(c.getKey()+"--"+c.getValue()));
    }
}