正确重写equals()和hashCode()方法

来源：互联网发布：欧洲旅游价格知乎编辑：程序博客网时间：2024/05/21 09:02

比较两个Java对象时, 如果相同的对象有不同的hashCode，比较操作会出现意想不到的结果，为了避免这种问题，要同时复写equals方法和hashCode方法，而不要只写其中一个。

class People {    String name;    int age;    public People(String name, int age) {        this.age = age;        this.name = name;    }    @Override    public boolean equals(Object obj) {        if (obj == this) {            return true;        }        if (!(obj instanceof People)) {            return false;        }        People people = (People) obj;        return people.name.equals(name) && people.age == age;    }    @Override    public int hashCode() {        int result = 17;        result = 31 * result + name.hashCode();        result = 31 * result + age;        return result;    }}public class Main {    public static void main(String[] args) {        People people1 = new People("程", 22);        People people2 = new People("程", 22);                People people3 = new People("程", 13);        System.out.println(people1.equals(people2));        System.out.println(people1.equals(people3));    }}

运行结果

truefalse

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