//父类 package oop.demo08; public class Person { public void run(){ System.out.println("run"); } } //子类 package oop.demo08; public class Student extends Person{ public void go(){ System.out.println("go"); } } //子类 package oop.demo08; public class Teacher extends Person{ } //测试 //instanceof的使用 //x instanceof y 能否编译通过,取决于x和y是否存在父子关系 public static void main(String[] args) { //Object > String //Object>Person>Student //Object>Person>Teacher Object object= new Student(); System.out.println(object instanceof Student);//true System.out.println(object instanceof Person);//true System.out.println(object instanceof Object);//true System.out.println(object instanceof Teacher);//false System.out.println(object instanceof String);//false System.out.println("=================="); Person person=new Student(); System.out.println(person instanceof Student);//true System.out.println(person instanceof Person);//true System.out.println(person instanceof Object);//true System.out.println(person instanceof Teacher);//false // System.out.println(person instanceof String);//编译报错 System.out.println("==================="); }