java - Java中删除重复的对象

Question

我的用户对象如下所示:

用户.java:

    public class User {
        public String firstName;
        public String lastName;

        public String getFirstName() {
            return firstName;
        }   
        public void setFirstName(String firstName) {
            this.firstName = firstName;
        }
        public String getLastName() {
            return lastName;
        }
        public void setLastName(String lastName) {
            this.lastName = lastName;
        }

        @Override
        public int hashCode() {
            return (this.firstName.hashCode() + this.lastName.hashCode());
        }

        @Override
        public boolean equals(Object obj) {
            if(obj instanceof User) {
                User temp = (User) obj;
                if(this.firstName.equals(temp.firstName) && this.lastName.equals(temp.lastName)) {
                    return true;
                }
            }
            return false;
        }
    }

主程序如下所示:

    import java.util.*; 

    class pp {
        public static void main(String[] args) {
            List<User[]> a = new ArrayList<User[]>();
            User[] u = new User[3];

            u[0] = new User();
            u[0].setFirstName("Mike"); u[0].setLastName("Jordon");      

            u[1] = new User();
            u[1].setFirstName("Jack"); u[1].setLastName("Nicolson");

            u[2] = new User();
            u[2].setFirstName("Jack"); u[2].setLastName("Nicolson");

            a.add(u);

            Set<User[]> s = new HashSet<User[]>(a);

            for (User[] ss : s) {
                for (int i=0; i<ss.length; i++) {           
                    System.out.println(ss[i].getFirstName() + " " + ss[i].getLastName());
                }
            }
        }
    }

我期望输出为

Mike Jordon
Jack Nicolson

但不知何故，它保留重复的对象并打印为:

Mike Jordon
Jack Nicolson
Jack Nicolson

谁能告诉我我错过了什么？

谢谢!

Answer 1

你的 equals 方法应该是这样的:

  @Override
    public boolean equals(Object obj) {
        if(obj instanceof User) {
            User temp = (User) obj;
            if(this.firstName.equals(temp.firstName) && this.lastName.equals(temp.lastName)) {
                return true;
            }
        }
        return false;
    }