java中解决list集合里对象重复问题

import java.util.*;
public class TestSet {
public static void main(String[] args) {
User u1 = new User("aa","11");

User u2 = new User("aa","11");
Set sets = new HashSet();
sets.add(u1);
sets.add(u2);
//  sets.remove(u1);//删除点一个User对象，然后进行验证  试验结果成功
System.out.println(sets.size());
System.out.println(sets);
}
}
class User{
String name;
String password;
User(String name,String password){
this.name=name;
this.password=password;
}
public String toString(){
return "Name :"+name+"  "+"Password:"+password;
}
public boolean equals(Object obj){
if(obj instanceof User){
User user=(User)obj;
return (name.equals(user.name))&&(password.equals(user.password));
}
return super.equals(obj);
}
public int hashCode(){
return name.hashCode();
}
}