HashSet 非重元素的拒绝添加

package com.conpany.hashset;

import java.util.HashSet;

class Person{
String name;
int id;

public Person(String name,int id){    this.id=id;    this.name=name;}@Overridepublic String toString() {    return "{ 名字:"+this.name+"  号码:"+this.id+"}";} @Overridepublic boolean equals(Object obj) {//决定了目标相同后的比较    Person p=(Person)obj;    return this.id==p.id;}@Overridepublic int hashCode() {//hashcode 决定在hashtable 中的位置    return this.id;}

}
public class Demo1 {
public static void main(String[] args) {
HashSet set=new HashSet();
set.add(new Person(“小工”,110));
set.add(new Person(“小里”,220));
set.add(new Person(“小黑”,330));
set.add(new Person(“小工”,110));

    System.out.println(set);}

}