InstanceOf关键字

左边是对象，右边是类，当对象是右边类或子类所创建的对象时，返回true，反之则为false

Object object = new Student();
System.out.println(object instanceof Student);
System.out.println(object instanceof Person);
System.out.println(object instanceof Object);
System.out.println(object instanceof Teacher);
System.out.println(object instanceof String);
运行结果：
true
true
true
false  Teacher类和Student类都继承了Person类 属于同级关系 所以输出为false
false  String类和Student类没有关系，所以输出为false