public class Vector <E>
extends AbstractList <E>
implements List<E>, RandomAccess, Cloneable, Serializable
The Vector class implements a growable array of objects. Like an array, it contains components that can be accessed using an integer index. However, the size of a Vector can grow or shrink as needed to accommodate adding and removing items after the Vector has been created.
Vector，繼承自AbstractList，實現了List<E>, RandomAccess, Cloneable, Serializable。
是一個可增長的"數組類"，向量和數組很像，可以用整數下標索引。但它可以放大/縮小容量、加添、刪除元素。
Fields，Vector提供的3個屬性變量：
Constructor 4個構造方法：
主要 Method：
