在父类中定义了final的方法，则在对应点的子类中不能被重写，也就是我们要求要在子类中不能被重写，应该在父类的方法中添加final修饰符

-In the parent class defines the final approach, subclasses of the corresponding points can t be rewritten, namely we require to be in subclasses can t be rewritten, should be added in the superclass method final modifier