利用HashSet对对象去重

HashSet去重：先判断hashCode（）是否相同，相同才会判断equals()

如果是需要对我们自定义的对象去重，就需要我们重写 hashCode 和 equals 方法

package com.huang;

import java.util.HashSet;
import java.util.Objects;
import java.util.Set;

public class Test {
    public static void main(String[] args) {
        User u = new User(10,"张三");
        User u2 = new User(10,"张三");
        User u3 = new User(10,"里斯");

        Set<User> set = new HashSet<>();
        set.add(u);
        set.add(u2);
        set.add(u3);

        for (User user : set) {
            System.out.println(user.age + user.name);
        }

    }

     private static class User {
        String name;
        Integer age;

        public User(){

        }
        public User(Integer age, String name){
            this.age = age;
            this.name = name;
        }

         @Override
         public boolean equals(Object o) {
             if (this == o) return true;
             if (o == null || getClass() != o.getClass()) return false;
             User user = (User) o;
             return Objects.equals(name, user.name) &&
                     Objects.equals(age, user.age);
         }

         @Override
         public int hashCode() {
             return Objects.hash(name, age);
         }
     }
}

执行结果如下，去重成功

利用HashSet对对象去重

原文：https://www.cnblogs.com/huangpeideng/p/13624049.html