package lxh.demo.listdemo;

import java.util.Enumeration;

import java.util.Iterator;

import java.util.List;

import java.util.Vector;

/*

* Vector遍历方式和效率的测试程序

*/

public class VectorRandomAccessTest {

public static void main(String[] args) {

Vector vec = new Vector();

for(int i = 0; i < 100000; i++) {

vec.add(i);

}

iteratorThroughRandomAccess(vec);

iteratorThroughIterator(vec);

iteratorThroughFor2(vec);

iteratorThroughEnumeration(vec);

}

/*

* 随机访问，通过索引值去遍历

*/

public static void iteratorThroughRandomAccess(List list) {

long startTime = System.currentTimeMillis();

for(int i = 0; i < list.size(); i++) {

list.get(i);

}

long endTime = System.currentTimeMillis();

System.out.println("iteratorThroughRandomAccess: " + (endTime-startTime) + "ms");

}

/*

* 通过迭代器遍历

*/

public static void iteratorThroughIterator(List list) {

long startTime = System.currentTimeMillis();

for(Iterator iter = list.iterator(); iter.hasNext();) {

iter.next();

}

long endTime = System.currentTimeMillis();

System.out.println("iteratorThroughIterator: " + (endTime-startTime) + "ms");

}

/*

* 增强for循环

*/

public static void iteratorThroughFor2(List list) {

long startTime = System.currentTimeMillis();

for(Object ojb : list) {

;

}

long endTime = System.currentTimeMillis();

System.out.println("iteratorThroughFor2: " + (endTime-startTime) + "ms");

}

/*

* Enumeration遍历

*/

public static void iteratorThroughEnumeration(Vector vec) {

long startTime = System.currentTimeMillis();

for(Enumeration enu = vec.elements(); enu.hasMoreElements();) {

enu.nextElement();

}

long endTime = System.currentTimeMillis();

System.out.println("iteratorThroughEnumeration: " + (endTime-startTime) + "ms");

}

}

package lxh.demo.listdemotest;

import java.util.Enumeration;

import java.util.Vector;

/*

* Vector测试函数

*/

public class VectorTest01 {

public static void main(String[] args) {

//新建Vector

Vector vec = new Vector();

//添加元素

vec.add("1");

vec.add("2");

vec.add("3");

vec.add("4");

vec.add("5");

//设置第一个元素为100

vec.set(0, "100");

//将500插入到第3个位置

vec.add(2, "500");

//将500插入到第4个位置

vec.add(2, "500");

System.out.println("vec: " + vec);

//第一次出现的索引

System.out.println("vec.indexOf(100): " + vec.indexOf("500"));

//最后一次出现的索引

System.out.println("vec.lastIndexOf(500): " + vec.lastIndexOf("500"));

//获得第一个元素

System.out.println("vec.firstElement(): " + vec.firstElement());

//获得第三个元素

System.out.println("vec.elementAt(2): " + vec.elementAt(2));

//获得最后一个元素

System.out.println("vec.lastElement(): " + vec.lastElement());

//获取Vector的大小

System.out.println("size: " + vec.size());

//获得Vector的总的容量

System.out.println("capacity: " + vec.capacity());

//获取Vector的第二到第四个元素

System.out.println("vec 2 to 4: " + vec.subList(1, 4));

//通过Enumeration遍历Vector

Enumeration enu = vec.elements();

while(enu.hasMoreElements()) {

System.out.println("nextElement(): " + enu.nextElement());

}

Vector retainVec = new Vector();

retainVec.add("100");

retainVec.add("300");

//获取vec中包含在retainVec中的元素的集合

System.out.println("vec.retain(): " + vec.retainAll(retainVec));

System.out.println("vec: " + vec);

//获取vec对应的String数组

String[] arr = (String[]) vec.toArray(new String[0]);

for(String str:arr) {

System.out.println("str: " +str);

}

//清空Vector

vec.clear();

//判断Vector是否为空

System.out.println("vec.isEmpty(): " + vec.isEmpty());

}

}