ArrayList真的比LinkedList慢吗

来源：互联网发布：中国高铁出口数据编辑：程序博客网时间：2024/04/28 06:09

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

public class WhichIsFaster
{
List<Integer> a = new ArrayList<Integer>();
List<Integer> l = new LinkedList<Integer>();

long timeStart[] = new long[2];
long timeEnd[] = new long[2];

Random r = new Random();

public void testAdd()
{
  System.out.println("/n------------随机添加-----------------/n");

  for (int i = 0; i < 10000; i++)
  {
   a.add(null);
   l.add(null);
  }

  timeStart[0] = System.currentTimeMillis();
  for (int i = 0; i < 10000; i++)
  {
   a.set(r.nextInt(10000), r.nextInt(10000));
  }
  timeEnd[0] = System.currentTimeMillis();

  timeStart[1] = System.currentTimeMillis();
  for (int i = 0; i < 10000; i++)
  {
   l.set(r.nextInt(10000),r.nextInt(10000));
  }
  timeEnd[1] = System.currentTimeMillis();

  System.out.println("ArrayList 用时/t:" + (timeEnd[0] - timeStart[0]));
  System.out.println("LinkedList 用时/t:" + (timeEnd[1] - timeStart[1]));

}

public void testGet()
{
  System.out.println("/n------------随机存取-----------------/n");

  timeStart[0] = System.currentTimeMillis();
  for (int i = 0; i < 100000; i++)
  {
   a.get(r.nextInt(10000));
  }
  timeEnd[0] = System.currentTimeMillis();

  timeStart[1] = System.currentTimeMillis();
  for (int i = 0; i < 100000; i++)
  {
   l.get(r.nextInt(10000));
  }
  timeEnd[1] = System.currentTimeMillis();

  System.out.println("ArrayList 用时/t:" + (timeEnd[0] - timeStart[0]));
  System.out.println("LinkedList 用时/t:" + (timeEnd[1] - timeStart[1]));

}

public void testDel()
{
  System.out.println("/n------------随机删除-----------------/n");

  timeStart[0] = System.currentTimeMillis();
  for (int i = 0; i < 1000; i++)
  {
   a.remove(r.nextInt(a.size()));
  }
  timeEnd[0] = System.currentTimeMillis();

  timeStart[1] = System.currentTimeMillis();
  for (int i = 0; i < 10000; i++)
  {
   l.remove(r.nextInt(l.size()));
  }
  timeEnd[1] = System.currentTimeMillis();

  System.out.println("ArrayList 用时/t:" + (timeEnd[0] - timeStart[0]));
  System.out.println("LinkedList 用时/t:" + (timeEnd[1] - timeStart[1]));

}

public static void main(String[] args)
{
  WhichIsFaster t = new WhichIsFaster();
  t.testAdd();
  t.testGet();
  t.testDel();
}

// 把100000换成10000试一试
}

===================================================================

------------随机添加-----------------

ArrayList 用时 :0
LinkedList 用时 :94

------------随机存取-----------------

ArrayList 用时 :0
LinkedList 用时 :1656

------------随机删除-----------------

ArrayList 用时 :32
LinkedList 用时 :78