B和implements之间需要逗号么？谢谢
no need, here is an example->
from java2SE5.0 API
public class ArrayList<E> extends AbstractList<E>implements List<E>, RandomAccess, Cloneable, Serializable
public class ArrayList<E> extends AbstractList<E>implements List<E>, RandomAccess, Cloneable, Serializable
Huasing Association 1999 - 2013