Java 数据结构 --> Vector 类

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Vector类实现了一个动态数组。和ArrayList和相似，但是两者是不同的：
Vector是同步访问的。
Vector包含了许多传统的方法，这些方法不属于集合框架。

Vector主要用在事先不知道数组的大小，或者只是需要一个可以改变大小的数组的情况。

public static void main(String args[]) {
// initial size is 3, increment is 2
Vector v = new Vector(3, 2);
System.out.println("Initial size: " + v.size());
System.out.println("Initial capacity: " +v.capacity());
v.addElement(new Integer(1));
v.addElement(new Integer(2));
v.addElement(new Integer(3));
v.addElement(new Integer(4));
System.out.println("Capacity after four additions: " +v.capacity());

v.addElement(new Double(5.45));
System.out.println("Current capacity: " +v.capacity());
v.addElement(new Double(6.08));
v.addElement(new Integer(7));
System.out.println("Current capacity: " +v.capacity());
v.addElement(new Float(9.4));
v.addElement(new Integer(10));
System.out.println("Current capacity: " +v.capacity());
v.addElement(new Integer(11));
v.addElement(new Integer(12));
System.out.println("First element: " +(Integer)v.firstElement());
System.out.println("Last element: " +(Integer)v.lastElement());
if(v.contains(new Integer(3)))
System.out.println("Vector contains 3.");
// enumerate the elements in the vector.
Enumeration vEnum = v.elements();
System.out.println("\nElements in vector:");
while(vEnum.hasMoreElements())
System.out.print(vEnum.nextElement() + " ");
System.out.println();
}

运行结果：

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

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