潜在的问题是您使用 getter 方法获取信息并对其进行操作.此处违反的原则是告诉，不要问！.

The underlaying problem is that you use a getter method to aquire an information and act on it. The principle which is violated here is Tell, don't ask!.

OO解决此问题的方法是引入接口(例如:PlayerMovingListener).

The OO whay to solve this is to introduce an interface (e.g.: PlayerMovingListener).

player类将包含实现该接口的对象的实例(或它们的列表).播放器一开始走动，就会调用由播放器所拥有的(或所有)侦听器对象实现的接口中定义的isMoving()方法.
^{很可能是由当前Payer实现中的setter方法触发的.}

The player class would hold an instance of an object implementing that interface (or a list of them). As soon as the player starts walking it calls the isMoving() method defined in the interface implemented by the (or all) listener object(s) held by the player.
^{Most likely is triggered by a setter method in your current Payer implementation.}