Java 集合-Set接口简析
在java doc中Set接口的描述如下:
public interface Setextends Collection;// 继承了Collection接口的所有操作;A collection that contains no duplicate elements. More formally, sets contain no pair of elements e1 and e2 such that e1.equals(e2), and at most one null element. As implied by its name, this interface models the m ...