Vector实现了动态数组。它类似于ArrayList，线程同步sychronized。
以下是vector类提供的构造函数的列表。
| Sr.No. | Constructor & Remark |
|---|---|
| 1 |
Vector() 此构造函数创建一个默认向量，其初始大小为10。 |
| 2 |
Vector(int size) 此构造函数接受等于所需大小的参数，并创建一个向量，其初始容量由大小指定。 |
| 3 |
Vector(int size，int incr) 此构造函数创建一个向量，其初始容量由大小指定，其增量由incr指定。 |
| 4 |
Vector(Collection c) 此构造函数创建一个包含集合c的元素的向量。 |
除了从其父类继承的方法外，Vector还定义了以下方法-
| Sr.No. | Method & Remark |
|---|---|
| 1 |
void add(int index，Object element) 将指定的元素插入此Vector中的指定位置。 |
| 2 |
boolean add(Object o) 将指定的元素附加到此Vector的末尾。 |
| 3 |
boolean addAll(Collection c) 按照指定Collection的Iterator返回的顺序，将指定Collection中的所有元素附加到此Vector的末尾。 |
| 4 |
boolean addAll(int index，Collection c) 将指定Collection中的所有元素插入此Vector中的指定位置。 |
| 5 |
void addElement(Object obj) 将指定的分量添加到此向量的末尾，将其大小增加一。 |
| 6 |
int Capacity() 返回此向量的当前容量。 |
| 7 |
void clear() 从此向量中删除所有元素。 |
| 8 |
Object clone() 返回此向量的副本。 |
| 9 |
boolean contains(Object elem) 判断是否包含elem对象 |
| 10 |
boolean containsAll(Collection c) 判断是否包含指定Collection中的所有元素，则返回true。 |
| 11 |
void copyInto(Object [] anArray) 将此向量的元素复制到指定的数组中。 |
| 12 |
Object elementAt(int index) 返回指定索引处的组件。 |
| 13 |
Enumeration elements() 返回此向量的组成部分的枚举。 |
| 14 |
void sureCapacity(int minCapacity) 如有必要，增加此向量的容量，以确保它至少可以容纳最小容量参数指定的组件数。 |
| 15 |
boolean equals(Object o) 比较指定对象是否相等。 |
| 16 |
Object firstElement() 返回第一个元素(索引为0的项目)。 |
| 17 |
Object get(int index) 返回指定位置的元素。 |
| 18 |
int hashCode() 返回hashCode值。 |
| 19 |
int indexOf(Object elem) 搜索给定参数的第一个匹配项，使用equals方法判断是否相等。 |
| 20 |
int indexOf(Object elem.int index) 搜索给定参数的第一次出现，从索引处开始搜索，并使用equals方法判断是否相等。 |
| 21 |
void insertElementAt(Object obj，int index) 将指定对象作为组件插入指定索引处。 |
| 22 |
boolean isEmpty() 判断是否为空。 |
| 23 |
Object lastElement() 返回最后一个元素。 |
| 24 |
int lastIndexOf(Object elem) 返回指定对象最后一次出现的索引。 |
| 25 |
int lastIndexOf(Object elem，int index) 从指定的索引开始向后搜索指定的对象，并向其返回索引。 |
| 26 |
Object remove(int index) 移除指定位置的元素。 |
| 27 |
boolean remove(Object o) 移除第一次出现的对象，如果向量不包含该对象，则该对象不变。 |
| 28 |
boolean removeAll(Collection c) 移除所有包含在指定Collection中的元素。 |
| 29 |
void removeAllElements() 删除所有元素，并将其大小设置为零。 |
| 30 |
boolean removeElement(Object obj) 删除参数的第一个对象。 |
| 31 |
void removeElementAt(int index) removeElementAt(int index)。 |
| 32 |
protected void removeRange(int fromIndex，int toIndex) 从此列表中删除索引在fromIndex(包括)和toIndex(不包括)之间的所有元素。 |
| 33 |
boolean keepAll(Collection c) 仅保留包含在指定Collection中的元素。 |
| 34 |
Object set(int index，Object element) 用指定元素替换指定位置的元素。 |
| 35 |
void setElementAt(Object obj，int index) 将指定索引处的组件设置为指定对象。 |
| 36 |
void setSize(int newSize) 设置大小。 |
| 37 |
int size() 返回大小数。 |
| 38 |
List subList(int fromIndex，int toIndex) 返回此列表中fromIndex(包括)和toIndex(不包括)之间的元素。 |
| 39 |
Object [] toArray() 返回所有元素的数组。 |
| 40 |
Object [] toArray(Object [] a) 返回所有元素的数组；返回数组的运行时类型是指定数组的运行时类型。 |
| 41 |
String toString() 返回此向量的字符串表示形式，其中包含每个元素的String表示形式。 |
| 42 |
void trimToSize() 将该向量的容量修整为向量的当前大小。 |
Vector 示例
以下程序说明了此集合支持的几种方法-
import java.util.*;
public class VectorDemo {
public static void main(String args[]) {
//初始大小为 3，增量为 2
Vector v=new Vector(3, 2);
System.out.println("Initial size: " + v.size());
System.out.println("Initial capacity: " + v.capacity());
v</span><span class="pun">.</span><span class="pln">addElement</span><span class="pun">(</span><span class="kwd">new</span><span class="pln"> </span><span class="typ">Integer</span><span class="pun">(</span><span class="lit">1</span><span class="pun">));</span><span class="pln">
v</span><span class="pun">.</span><span class="pln">addElement</span><span class="pun">(</span><span class="kwd">new</span><span class="pln"> </span><span class="typ">Integer</span><span class="pun">(</span><span class="lit">2</span><span class="pun">));</span><span class="pln">
v</span><span class="pun">.</span><span class="pln">addElement</span><span class="pun">(</span><span class="kwd">new</span><span class="pln"> </span><span class="typ">Integer</span><span class="pun">(</span><span class="lit">3</span><span class="pun">));</span><span class="pln">
v</span><span class="pun">.</span><span class="pln">addElement</span><span class="pun">(</span><span class="kwd">new</span><span class="pln"> </span><span class="typ">Integer</span><span class="pun">(</span><span class="lit">4</span><span class="pun">));</span><span class="pln">
</span><span class="typ">System</span><span class="pun">.</span><span class="kwd">out</span><span class="pun">.</span><span class="pln">println</span><span class="pun">(</span><span class="str">"Capacity after four additions: "</span><span class="pln"> </span><span class="pun">+</span><span class="pln"> v</span><span class="pun">.</span><span class="pln">capacity</span><span class="pun">());</span><span class="pln">
v</span><span class="pun">.</span><span class="pln">addElement</span><span class="pun">(</span><span class="kwd">new</span><span class="pln"> </span><span class="typ">Double</span><span class="pun">(</span><span class="lit">5.45</span><span class="pun">));</span><span class="pln">
</span><span class="typ">System</span><span class="pun">.</span><span class="kwd">out</span><span class="pun">.</span><span class="pln">println</span><span class="pun">(</span><span class="str">"Current capacity: "</span><span class="pln"> </span><span class="pun">+</span><span class="pln"> v</span><span class="pun">.</span><span class="pln">capacity</span><span class="pun">());</span><span class="pln">
v</span><span class="pun">.</span><span class="pln">addElement</span><span class="pun">(</span><span class="kwd">new</span><span class="pln"> </span><span class="typ">Double</span><span class="pun">(</span><span class="lit">6.08</span><span class="pun">));</span><span class="pln">
v</span><span class="pun">.</span><span class="pln">addElement</span><span class="pun">(</span><span class="kwd">new</span><span class="pln"> </span><span class="typ">Integer</span><span class="pun">(</span><span class="lit">7</span><span class="pun">));</span><span class="pln">
</span><span class="typ">System</span><span class="pun">.</span><span class="kwd">out</span><span class="pun">.</span><span class="pln">println</span><span class="pun">(</span><span class="str">"Current capacity: "</span><span class="pln"> </span><span class="pun">+</span><span class="pln"> v</span><span class="pun">.</span><span class="pln">capacity</span><span class="pun">());</span><span class="pln">
v</span><span class="pun">.</span><span class="pln">addElement</span><span class="pun">(</span><span class="kwd">new</span><span class="pln"> </span><span class="typ">Float</span><span class="pun">(</span><span class="lit">9.4</span><span class="pun">));</span><span class="pln">
v</span><span class="pun">.</span><span class="pln">addElement</span><span class="pun">(</span><span class="kwd">new</span><span class="pln"> </span><span class="typ">Integer</span><span class="pun">(</span><span class="lit">10</span><span class="pun">));</span><span class="pln">
</span><span class="typ">System</span><span class="pun">.</span><span class="kwd">out</span><span class="pun">.</span><span class="pln">println</span><span class="pun">(</span><span class="str">"Current capacity: "</span><span class="pln"> </span><span class="pun">+</span><span class="pln"> v</span><span class="pun">.</span><span class="pln">capacity</span><span class="pun">());</span><span class="pln">
v</span><span class="pun">.</span><span class="pln">addElement</span><span class="pun">(</span><span class="kwd">new</span><span class="pln"> </span><span class="typ">Integer</span><span class="pun">(</span><span class="lit">11</span><span class="pun">));</span><span class="pln">
v</span><span class="pun">.</span><span class="pln">addElement</span><span class="pun">(</span><span class="kwd">new</span><span class="pln"> </span><span class="typ">Integer</span><span class="pun">(</span><span class="lit">12</span><span class="pun">));</span><span class="pln">
</span><span class="typ">System</span><span class="pun">.</span><span class="kwd">out</span><span class="pun">.</span><span class="pln">println</span><span class="pun">(</span><span class="str">"First element: "</span><span class="pln"> </span><span class="pun">+</span><span class="pln"> </span><span class="pun">(</span><span class="typ">Integer</span><span class="pun">)</span><span class="pln">v</span><span class="pun">.</span><span class="pln">firstElement</span><span class="pun">());</span><span class="pln">
</span><span class="typ">System</span><span class="pun">.</span><span class="kwd">out</span><span class="pun">.</span><span class="pln">println</span><span class="pun">(</span><span class="str">"Last element: "</span><span class="pln"> </span><span class="pun">+</span><span class="pln"> </span><span class="pun">(</span><span class="typ">Integer</span><span class="pun">)</span><span class="pln">v</span><span class="pun">.</span><span class="pln">lastElement</span><span class="pun">());</span><span class="pln">
</span><span class="kwd">if</span><span class="pun">(</span><span class="pln">v</span><span class="pun">.</span><span class="pln">contains</span><span class="pun">(</span><span class="kwd">new</span><span class="pln"> </span><span class="typ">Integer</span><span class="pun">(</span><span class="lit">3</span><span class="pun">)))</span><span class="pln">
</span><span class="typ">System</span><span class="pun">.</span><span class="kwd">out</span><span class="pun">.</span><span class="pln">println</span><span class="pun">(</span><span class="str">"Vector contains 3."</span><span class="pun">);</span><span class="pln">
</span><span class="com">//枚举向量中的元素。</span><span class="pln">
</span><span class="typ">Enumeration</span><span class="pln"> vEnum</span><span class="pun">=</span><span class="pln">v</span><span class="pun">.</span><span class="pln">elements</span><span class="pun">();</span><span class="pln">
</span><span class="typ">System</span><span class="pun">.</span><span class="kwd">out</span><span class="pun">.</span><span class="pln">println</span><span class="pun">(</span><span class="str">"\nElements in vector:"</span><span class="pun">);</span><span class="pln">
</span><span class="kwd">while</span><span class="pun">(</span><span class="pln">vEnum</span><span class="pun">.</span><span class="pln">hasMoreElements</span><span class="pun">())</span><span class="pln">
</span><span class="typ">System</span><span class="pun">.</span><span class="kwd">out</span><span class="pun">.</span><span class="kwd">print</span><span class="pun">(</span><span class="pln">vEnum</span><span class="pun">.</span><span class="pln">nextElement</span><span class="pun">()</span><span class="pln"> </span><span class="pun">+</span><span class="pln"> </span><span class="str">" "</span><span class="pun">);</span><span class="pln">
</span><span class="typ">System</span><span class="pun">.</span><span class="kwd">out</span><span class="pun">.</span><span class="pln">println</span><span class="pun">();</span><span class="pln">
}
}
这将产生以下输出-
Initial size: 0 Initial capacity: 3 Capacity after four additions: 5 Current capacity: 5 Current capacity: 7 Current capacity: 9 First element: 1 Last element: 12 Vector contains 3.Elements in vector: 1 2 3 4 5.45 6.08 7 9.4 10 11 12
