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HashSet存储自定义类型元素

必须重写hashCode和toString方法

package com.itheima.demo02.Set;

import java.util.HashSet;

HashSet存储自定义类型元素

set集合报错元素唯一:
    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

public class Demo03HashSetSavePerson {

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);
}

}

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;
}

}

原文 https://segmentfault.com/a/1190000019635393

正文到此结束