为什么还是有重复的输出？

目的：（考察知识点：如何在HashSet集合中添加自定义对象）

import java.util.HashSet;
class Student{
    private String name;
    private int age;
    public Student(String name,int age){
        this.age=age;
        this.name=name;
    }
    public String toString(){
        return "name:"+name+" age:"+age;
    }
    public int hashcode(){
        return name.hashCode();
    }
    public boolean equals(Object obj){
        Student stu=(Student) obj;
        boolean b=this.name.equals(stu.name);
        return b;
    }
}
public class hashmap3 {

    public static void main(String[] args) {
        HashSet hs=new HashSet();
        Student s1=new Student("大美女",11);
        Student s2=new Student("小美女",12);
        Student s3=new Student("小美女",12);
        hs.add(s1);
        hs.add(s2);
        hs.add(s3);
        System.out.println(hs);
    }
}

这不是重复的吗

Set<Student> hs = new Hashset<student>();

改成这样再试试看