ArrayList和LinkedList的区别
Posted 涤新云
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一般大家都知道ArrayList和LinkedList的大致区别:
1.ArrayList是实现了基于动态数组的数据结构,LinkedList基于链表的数据结构。
2.对于随机访问get和set,ArrayList觉得优于LinkedList,因为LinkedList要移动指针。
3.对于新增和删除操作add和remove,LinedList比较占优势,因为ArrayList要移动数据。
这一点要看实际情况的。若只对单条数据插入或删除,ArrayList的速度反而优于LinkedList。但若是批量随机的插入删除数据,LinkedList的速度大大优于ArrayList. 因为ArrayList每插入一条数据,要移动插入点及之后的所有数据。 这一点我做了实验。在分别有200000条“记录”的ArrayList和LinkedList的首位插入20000条数据,LinkedList耗时约是ArrayList的20分之1。
![技术分享](https://image.cha138.com/20200808/f8d7a9a08a944a0abeeb55af2e68a80c.jpg)
for(int m=0;m<20000;m++){
![技术分享](https://image.cha138.com/20200808/1fd336d6a5044eabbdb4b9df1766d408.jpg)
linkedlist.add(m,null); //当在200000条数据之前插入20000条数据时,LinkedList只用了1125多ms.这就是LinkedList的优势所在
![技术分享](https://image.cha138.com/20200808/dc130d458c694a15b74a5abad9dc7284.jpg)
}
![技术分享](https://image.cha138.com/20200808/5ecdc8362cc440b085b765c056dca3c6.jpg)
long time4 = new Dte().getTime();
![技术分享](https://image.cha138.com/20200808/5ecdc8362cc440b085b765c056dca3c6.jpg)
System.out.print("batch linkedlist add:");
![技术分享](https://image.cha138.com/20200808/5ecdc8362cc440b085b765c056dca3c6.jpg)
System.out.println(time4 - time3);
![技术分享](https://image.cha138.com/20200808/f8d7a9a08a944a0abeeb55af2e68a80c.jpg)
for(int n=0;n<20000;n++){
![技术分享](https://image.cha138.com/20200808/1fd336d6a5044eabbdb4b9df1766d408.jpg)
arraylist.add(n, null); //当在200000条数据之前插入20000条数据时,ArrayList用了18375多ms.时间花费是arraylist的近20倍(视测试时机器性能)
![技术分享](https://image.cha138.com/20200808/dc130d458c694a15b74a5abad9dc7284.jpg)
}
![技术分享](https://image.cha138.com/20200808/5ecdc8362cc440b085b765c056dca3c6.jpg)
long time5 = new Date().getTime();
![技术分享](https://image.cha138.com/20200808/5ecdc8362cc440b085b765c056dca3c6.jpg)
System.out.print("batch arraylist add:");
![技术分享](https://image.cha138.com/20200808/5ecdc8362cc440b085b765c056dca3c6.jpg)
System.out.println(time5 - time4);
4.查找操作indexOf,lastIndexOf,contains等,两者差不多。
5.随机查找指定节点的操作get,ArrayList速度要快于LinkedList.
这里只是理论上分析,事实上也不一定,ArrayList在末尾插入和删除数据的话,速度反而比LinkedList要快。我做过一个插入和删除200000条数据的试验。
![技术分享](https://image.cha138.com/20200808/5ecdc8362cc440b085b765c056dca3c6.jpg)
long time1 = new Date().getTime();
![技术分享](https://image.cha138.com/20200808/5ecdc8362cc440b085b765c056dca3c6.jpg)
String s1 = (String) linkedlist.get(100000);// 总记录200000,linkedlist加载第100000条数据耗时15~32ms不等
![技术分享](https://image.cha138.com/20200808/5ecdc8362cc440b085b765c056dca3c6.jpg)
long time2 = new Date().getTime();
![技术分享](https://image.cha138.com/20200808/5ecdc8362cc440b085b765c056dca3c6.jpg)
System.out.println(time2 - time1);
![技术分享](https://image.cha138.com/20200808/5ecdc8362cc440b085b765c056dca3c6.jpg)
String s2 = (String) arraylist.get(100000);// 总记录200000,linkedlist加载第100000条数据耗时0ms
![技术分享](https://image.cha138.com/20200808/5ecdc8362cc440b085b765c056dca3c6.jpg)
long time3 = new Date().getTime();
![技术分享](https://image.cha138.com/20200808/5ecdc8362cc440b085b765c056dca3c6.jpg)
System.out.println(time3 - time2);
![技术分享](https://image.cha138.com/20200808/f8d7a9a08a944a0abeeb55af2e68a80c.jpg)
/*分别insert200000条数据到linkedlist和arraylist
![技术分享](https://image.cha138.com/20200808/1fd336d6a5044eabbdb4b9df1766d408.jpg)
*由于是在末尾插入数据,arraylist的速度比linkedlist的速度反而要快
![技术分享](https://image.cha138.com/20200808/dc130d458c694a15b74a5abad9dc7284.jpg)
*/
![技术分享](https://image.cha138.com/20200808/f8d7a9a08a944a0abeeb55af2e68a80c.jpg)
public static void insertList(LinkedList linklist, ArrayList arraylist) {
![技术分享](https://image.cha138.com/20200808/1fd336d6a5044eabbdb4b9df1766d408.jpg)
long time1 = new Date().getTime();
![技术分享](https://image.cha138.com/20200808/1fd336d6a5044eabbdb4b9df1766d408.jpg)
System.out.println(time1);
![技术分享](https://image.cha138.com/20200808/aaba377d43634356a3adfe81a7525144.jpg)
for (int i = 0; i < 200000; i++) {
![技术分享](https://image.cha138.com/20200808/1fd336d6a5044eabbdb4b9df1766d408.jpg)
linklist.add(i, "linklist" + i);
![技术分享](https://image.cha138.com/20200808/54c291d758514a1ba271f11061993796.jpg)
}
![技术分享](https://image.cha138.com/20200808/1fd336d6a5044eabbdb4b9df1766d408.jpg)
long time2 = new Date().getTime();
![技术分享](https://image.cha138.com/20200808/1fd336d6a5044eabbdb4b9df1766d408.jpg)
System.out.println(time2 - time1);
![技术分享](https://image.cha138.com/20200808/aaba377d43634356a3adfe81a7525144.jpg)
for (int j = 0; j < 200000; j++) {
![技术分享](https://image.cha138.com/20200808/1fd336d6a5044eabbdb4b9df1766d408.jpg)
arraylist.add(j, "arraylist" + j);
![技术分享](https://image.cha138.com/20200808/54c291d758514a1ba271f11061993796.jpg)
}
![技术分享](https://image.cha138.com/20200808/1fd336d6a5044eabbdb4b9df1766d408.jpg)
long time3 = new Date().getTime();
![技术分享](https://image.cha138.com/20200808/1fd336d6a5044eabbdb4b9df1766d408.jpg)
System.out.println(time3 - time2);
![技术分享](https://image.cha138.com/20200808/dc130d458c694a15b74a5abad9dc7284.jpg)
}
![技术分享](https://image.cha138.com/20200808/5ecdc8362cc440b085b765c056dca3c6.jpg)
![技术分享](https://image.cha138.com/20200808/5ecdc8362cc440b085b765c056dca3c6.jpg)
![技术分享](https://image.cha138.com/20200808/f8d7a9a08a944a0abeeb55af2e68a80c.jpg)
/*delete linkedlist和arraylist中的200000条数据
![技术分享](https://image.cha138.com/20200808/1fd336d6a5044eabbdb4b9df1766d408.jpg)
*由于是在末尾删除数据,arraylist的速度比linkedlist的速度反而要快
![技术分享](https://image.cha138.com/20200808/dc130d458c694a15b74a5abad9dc7284.jpg)
*/
![技术分享](https://image.cha138.com/20200808/f8d7a9a08a944a0abeeb55af2e68a80c.jpg)
public static void deleteList(LinkedList linklist, ArrayList arraylist) {
![技术分享](https://image.cha138.com/20200808/1fd336d6a5044eabbdb4b9df1766d408.jpg)
long time1 = new Date().getTime();
![技术分享](https://image.cha138.com/20200808/1fd336d6a5044eabbdb4b9df1766d408.jpg)
System.out.println(time1);
![技术分享](https://image.cha138.com/20200808/aaba377d43634356a3adfe81a7525144.jpg)
for (int i = 199999; i >= 0; i--) {
![技术分享](https://image.cha138.com/20200808/1fd336d6a5044eabbdb4b9df1766d408.jpg)
linklist.remove(i);
![技术分享](https://image.cha138.com/20200808/54c291d758514a1ba271f11061993796.jpg)
}
![技术分享](https://image.cha138.com/20200808/1fd336d6a5044eabbdb4b9df1766d408.jpg)
long time2 = new Date().getTime();
![技术分享](https://image.cha138.com/20200808/1fd336d6a5044eabbdb4b9df1766d408.jpg)
System.out.println(time2 - time1);
![技术分享](https://image.cha138.com/20200808/aaba377d43634356a3adfe81a7525144.jpg)
for (int j = 199999; j >= 0; j--) {
![技术分享](https://image.cha138.com/20200808/1fd336d6a5044eabbdb4b9df1766d408.jpg)
arraylist.remove(j);
![技术分享](https://image.cha138.com/20200808/54c291d758514a1ba271f11061993796.jpg)
}
![技术分享](https://image.cha138.com/20200808/1fd336d6a5044eabbdb4b9df1766d408.jpg)
long time3 = new Date().getTime();
![技术分享](https://image.cha138.com/20200808/1fd336d6a5044eabbdb4b9df1766d408.jpg)
System.out.println(time3 - time2);
![技术分享](https://image.cha138.com/20200808/dc130d458c694a15b74a5abad9dc7284.jpg)
}
![技术分享](https://image.cha138.com/20200808/5ecdc8362cc440b085b765c056dca3c6.jpg)
![技术分享](https://image.cha138.com/20200808/f8d7a9a08a944a0abeeb55af2e68a80c.jpg)
public static void main(String args[]) {
![技术分享](https://image.cha138.com/20200808/1fd336d6a5044eabbdb4b9df1766d408.jpg)
LinkedList linkedlist = new LinkedList();
![技术分享](https://image.cha138.com/20200808/1fd336d6a5044eabbdb4b9df1766d408.jpg)
ArrayList arraylist = new ArrayList();
![技术分享](https://image.cha138.com/20200808/1fd336d6a5044eabbdb4b9df1766d408.jpg)
insertList(linkedlist, arraylist);
![技术分享](https://image.cha138.com/20200808/1fd336d6a5044eabbdb4b9df1766d408.jpg)
![技术分享](https://image.cha138.com/20200808/1fd336d6a5044eabbdb4b9df1766d408.jpg)
//以下代码省略
插入:
LinkedList 578ms
ArrayList 437ms
删除:
LinkedList 31ms
ArrayList 16ms
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