标签：测试 tar span == 存储空间 数据 大量 current 程序
按说HashMap的负载极限为0.75，可是，测试程序并看不出这个结果。待探讨
测试程序如下：
根据结果看不出来预定义有什么影响。
public class test { public static void main(String[] args) { testRun(5000000); testRun(10000000); testRun(15000000); testRun(20000000); testRun(25000000); testRun(30000000); testRun(35000000); testRun(40000000); testRun(45000000); testRun(50000000); } public static void testRun(int mapCount){ System.out.println("============"+mapCount+"============="); run(mapCount,new HashMap<>()); run(mapCount,new HashMap<>(mapCount)); run(mapCount,new HashMap<>((int)(mapCount/0.75))); run(mapCount,new HashMap<>((int)(mapCount/0.6))); run(mapCount,new HashMap<>((int)(mapCount/0.5))); } public static void run(int mapCount,Map<Integer,String> testMap){ String testValue = ""; Long startTime0 = System.currentTimeMillis(); for(int i = 1;i<mapCount;i++){ testMap.put(i, testValue); } Long endTime0 = System.currentTimeMillis(); System.out.println(endTime0-startTime0); } }
============5000000============= 1670 689 981 260 211 ============10000000============= 1097 4485 793 386 331 ============15000000============= 768 3394 2805 5651 6022 ============20000000============= 8155 2153 5089 6078 6809 ============25000000============= 8890 6998 10050 9149 10501 ============30000000============= 14467 10527 9334 11453 13733 ============35000000============= 14493 11978 13706 13809 11461 ============40000000============= 15788 13439 18142 13514 11351 ============45000000============= 12952 18501 17793 11894 30664 ============50000000============= 29528 14534 14272 32803 42236
标签：测试 tar span == 存储空间 数据 大量 current 程序
原文地址：http://www.cnblogs.com/lakeslove/p/7100916.html
