zoukankan      html  css  js  c++  java
  • Java精确测量代码运行时间 代码执行时间 纳秒 nanoTime

     

    Java精确测量代码运行时间:

            long startTime = System.nanoTime();  //開始時間         for(int i = 0;i<10000;i++){             ;         }         long consumingTime = System.nanoTime() - startTime; //消耗時間         System.out.println(consumingTime);         System.out.println(consumingTime/1000+"微秒");

    JDK的解释:

    public static long nanoTime()

    Returns the current value of the most precise available system timer, in nanoseconds.

    This method can only be used to measure elapsed time and is not related to any other notion of system or wall-clock time. The value returned represents nanoseconds since some fixed but arbitrary time (perhaps in the future, so values may be negative). This method provides nanosecond precision, but not necessarily nanosecond accuracy. No guarantees are made about how frequently values change. Differences in successive calls that span greater than approximately 292 years (263 nanoseconds) will not accurately compute elapsed time due to numerical overflow.

    For example, to measure how long some code takes to execute:

       long startTime = System.nanoTime();   // ... the code being measured ...   long estimatedTime = System.nanoTime() - startTime; 
  • 相关阅读:
    mysql常用函数
    主程Ry访谈录
    mongodb spring anno 查询
    mongodb 查询少少优化
    jquery table thead drop
    ubuntu 配置java,eclipse ,flex,zend,php,TomCat环境
    mongodb shell
    TCP/IP Sockets in Java 源码
    java 断点下载
    直线生成 DDA
  • 原文地址:https://www.cnblogs.com/shaohz2014/p/3599888.html
Copyright © 2011-2022 走看看