一个完整的遍历速度测试

一个完整的遍历速度测试：

import java.util.Iterator; import java.util.List; import java.util.ArrayList; import java.util.LinkedList; /** * IteratorTest * @author SageZk */ public class IteratorTest { public static long testForloops(List list) { long start = 0L, end = 0L; @SuppressWarnings("unused") String le = null; start = System.nanoTime(); for (int i = list.size() - 1; i >= 0; --i) { le = list.get(i); } end = System.nanoTime(); return end - start; } public static long testIterator(List list) { long start = 0L, end = 0L; @SuppressWarnings("unused") String le = null; start = System.nanoTime(); Iterator it = list.iterator(); while (it.hasNext()) { le = it.next(); } end = System.nanoTime(); return end - start; } public static void main(String[] args) { //测试列表长度 final int LEN = 10000; //初始化测试用数据 List arraylist = new ArrayList(); List linkedlist = new LinkedList(); for (int i = 0; i < LEN; ++i) { String s = Integer.toString(i, 2); arraylist.add(s); linkedlist.add(s); } //打印测试结果 final String FORMAT = "%1$-16s%2$-16s%3$16d/n"; System.out.println("List/t/tType/t/tTime(nanoseconds)"); System.out.println("-------------------------------------------------"); System.out.printf(FORMAT, "ArrayList", "for", testForloops(arraylist)); System.out.printf(FORMAT, "ArrayList", "Iterator", testIterator(arraylist)); System.out.printf(FORMAT, "LinkedList", "for", testForloops(linkedlist)); System.out.printf(FORMAT, "LinkedList", "Iterator", testIterator(linkedlist)); } }

 

以下是 3 组测试结果：

BatchFile code

List Type Time ( nanoseconds )
-------------------------------------------------
ArrayList for 1189258
ArrayList Iterator 2365594
LinkedList for 152396254
LinkedList Iterator 2340801

List Type Time ( nanoseconds )
-------------------------------------------------
ArrayList for 1235701
ArrayList Iterator 4249982
LinkedList for 149825606
LinkedList Iterator 2525531

List Type Time ( nanoseconds )
-------------------------------------------------
ArrayList for 1198267
ArrayList Iterator 2584617
LinkedList for 150382451
LinkedList Iterator 2347994