如何同时访问列表列表

I have a List of Lists , what i want to do is create threads which reads objects(list) and removes it from the "sharedList" , how can make the list threadsafe ? am using synchronizedList , but what if a thread removed and object while another thread was reading another object ? as .remove shifts the objects to the left ....I have a List of Lists , what i want to do is c