java之instanceof操作符

a intanceof A：判断a是否是类A的的一个实例，返回值为boolean

public class Person extends Object{}

public class Student extends Person{}

public class Graduate extends Person{}

public class Main {
    public static void main(String[] args) {
        Person p = new Person();
        Student s = new Student();
        Graduate g = new Graduate();    
        System.out.println(p instanceof Person);
        System.out.println(s instanceof Person);
        System.out.println(g instanceof Person);
    }
}

输出：

true

true

true