关于HashSet添加元素问题，大神来帮我看看

Question

import java.util.*;
class employee{
    private String id;
    private String name;
    private String age;
    private String salary;
    public employee(String id,String name,String age,String salary){
        this.id=id;
        this.name=name;
        this.age=age;
        this.salary=salary;
    }
    public String toString(){
        return id+":"+name+","+age+","+salary+"";    }
    public int hashcode(){
        return id.hashCode();
    }
    public boolean equals(Object obj){
        if(this==obj){
            return true;
        }
        if(!(obj instanceof employee)){
            return false;
        }
        employee emp=(employee)obj;
        boolean b=this.id.equals(emp.id);
        return b;    }}
public class information {    public static void main(String[] args) {
        HashSet hs=new HashSet();
        employee emp1=new employee("5","张三","25","3500");
        employee emp2=new employee("2","李四","30","4000");
        employee emp3=new employee("5","王五","40","5000");
        hs.add(emp1);
        hs.add(emp2);
        hs.add(emp3);
        System.out.print(hs);    }
}
我改写了hashcode()和equals()方法，为什么emp1和emp3这两个id都为5的对象都添加进去了？怎么不起作用？

Answer 1

 public int hashcode(){
        return id.hashCode();
    }方法中C需要大写，不然不算重写

Answer 2

你只用到了employee的构造器

Answer 3

 public int hashcode(){
        return id.hashCode();
    }方法中C需要大写，不然不算重写
厉害了，我说我怎么找不到错误呢

Answer 4

方法的重写加上@Override，这是规范，虽然有时候可能不加程序也能运行    @Override
    public int hashCode() {
        return super.hashCode();
    }