ArrayList和LinkedList插入删除效率的测试（完全不在一个数量级8/20）

通过index获取元素的值

java里面的链表可以添加索引，而C中的链表，是没有索引的

---

---

---

---

---

package ArrayListVSLinkedList;

import java.util.ArrayList;
import java.util.Date;
import java.util.LinkedList;
  ArrayList和LinkedList向后追加元素的性能比较
/**
 * Created by IntelliJ IDEA.
 * User: luhba
 * Date: 17-8-10
 * Time: 下午7:06
 * To change this template use File | Settings | File Templates.
 */
public class ArrayListVSLinkedList
{
     public static void ArrayListTest(long num)
     {
         ArrayList list = new ArrayList()  ;
         long berforeTime= new Date().getTime();
         for(int i=0;i<num;i++)
         {
             list.add(i,i);
         }
         long afterTime = new Date().getTime();
         System.err.println("The process ArrayListTest used a total time is "+(afterTime-berforeTime) +" millisecondes !" );
     }
    public static void linkedList(long num)
    {
        LinkedList  list = new LinkedList();
         long berforeTime= new Date().getTime();
         for(int i=0;i<num;i++)
         {
             list.add(i,i);
         }
         long afterTime = new Date().getTime();
         System.err.println("The process linkedList used a total time is "+(afterTime-berforeTime) +" millisecondes !" );
    }
    public static void main(String[] args)
    {
        ArrayListVSLinkedList.ArrayListTest(100000);
        ArrayListVSLinkedList.linkedList(100000);
    }
}

执行的结果是： 
The process ArrayListTest used a total time is 31 millisecondes ! 
The process linkedList used a total time is 32 millisecondes ! 

这个是为什么呢？顺序存储插入的速度竟然比链式存储的还要快？ 
答：这个例子是顺序存储的最理想的方式，不用向后移动一个element，所以速度相当。那么再举一个差别最大

---

---

---

---

---

 //数组和链表在头部插入数据的效率

import java.util.ArrayList;
import java.util.Date;
import java.util.LinkedList;
import java.util.List;

public class Hi{
     public static void ArrayListTest(long num){
         List list = new ArrayList()  ;
         long berforeTime= new Date().getTime();
         for(int i=0;i<num;i++){ //在数组的头部插入一个元素
             list.add(0,i);
         }
         long afterTime = new Date().getTime();
         System.err.println("The process ArrayListTest used a total time is "+(afterTime-berforeTime) +" millisecondes !" );
    
         long t1= new Date().getTime();
         while(!list.isEmpty()){
        	   while(!list.isEmpty()){
              	 list.remove(0);
               }
         }
         long t2 = new Date().getTime();
         System.err.println("数组删除"+(t2-t1));
     }
    public static void linkedList(long num){
         List  list = new LinkedList();
         long berforeTime= new Date().getTime();
         for(int i=0;i<num;i++) {
             list.add(0,i); /*添加元素：添加单个元素 
 　　　　　　　如果不指定索引的话，元素将被添加到链表的最后*/
         }
         long afterTime = new Date().getTime();
         System.err.println("The process linkedList used a total time is "+(afterTime-berforeTime) +" millisecondes !" );
         
         long t1= new Date().getTime();
         while(!list.isEmpty()){
        	 list.remove(0);
         }
         long t2 = new Date().getTime();
         System.err.println("链表删除"+(t2-t1));  
    } 
    public static void main(String[] args){
       Hi.ArrayListTest(99999*5);
       Hi.linkedList(99999*5);
    }
}