java——集合——Set集合——HashSet存储自定义类型元素——必须重写hashCode方法和equals方法，保证同名同年龄的人,视为同一个人,只能存储一次...

淡淡的烟草味﹌ 2023-09-28 23:28 11阅读 0赞

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> HashSet存储自定义类型元素

#### HashSet存储自定义类型元素 ####

*  set集合必须元素唯一:  
    存储的元素(String,Integer,...Student,Person...),必须重写hashCode方法和equals方法
 *  要求:  
    同名同年龄的人,视为同一个人,只能存储一次

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自定义元素

package com.itheima.demo02.Set;
    
    import java.util.Objects; public class Person { private String name; private int age; public Person() { } public Person(String name, int age) { this.name = name; this.age = age; } @Override public boolean equals(Object o) { if (this == o) return true; if (o == null || getClass() != o.getClass()) return false; Person person = (Person) o; return age == person.age && Objects.equals(name, person.name); } @Override public int hashCode() { return Objects.hash(name, age); } @Override public String toString() { return "Person{" + "name='" + name + '\'' + ", age=" + age + '}'; } public String getName() { return name; } public void setName(String name) { this.name = name; } public int getAge() { return age; } public void setAge(int age) { this.age = age; } }

测试类

public classDemo03HashSetSavePerson {
        public static void main(String[] args) { //创建HashSet集合存储Person HashSet<Person> set = new HashSet<>(); Person p1 = new Person("小美女",18); Person p2 = new Person("小美女",18); Person p3 = new Person("小美女",19); System.out.println(p1.hashCode());//1967205423 System.out.println(p2.hashCode());//42121758 System.out.println(p1==p2);//false System.out.println(p1.equals(p2));//false set.add(p1); set.add(p2); set.add(p3); System.out.println(set); } }

[deb2644d1196bad645dea1c733b94aa9.png]: https://img-blog.csdnimg.cn/img_convert/deb2644d1196bad645dea1c733b94aa9.png
[3a27a736ce93de4f8c55af38dfc778bc.png]: https://img-blog.csdnimg.cn/img_convert/3a27a736ce93de4f8c55af38dfc778bc.png
[3d4fff5b3e5484ada475192e79066d18.png]: https://img-blog.csdnimg.cn/img_convert/3d4fff5b3e5484ada475192e79066d18.png
[597b968f91524216213c2e09befb7edf.png]: https://img-blog.csdnimg.cn/img_convert/597b968f91524216213c2e09befb7edf.png
[3dbabf547b58991dd901345d84f1d81b.png]: https://img-blog.csdnimg.cn/img_convert/3dbabf547b58991dd901345d84f1d81b.png