instanceof和类型转换

instanceof和类型转换

测试类

import com.study_java.oop.Demo07.Student;
import com.study_java.oop.Demo07.Person;
import com.study_java.oop.Demo07.Teacher;

public class Application {
    public static void main(String[] args) {

        //Object->Person->Student
        //Object->Person->Teacher
        //Object->String
        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("===============================");
       Student student = new Student();
        System.out.println(student instanceof Student);//true
        System.out.println(student instanceof Person);//true
        System.out.println(student instanceof Object);//true
        //System.out.println(student instanceof Teacher);//编译报错
        //System.out.println(person instanceof String);//编译报错
    }

}

Person类

package com.study_java.oop.Demo07;

public class Person {
 
}

Student类

package com.study_java.oop.Demo07;

public class Student extends Person{

}

Teacher类

package com.study_java.oop.Demo07;

public class Teacher extends Person{
}