Java：计算代码耗时的5种方法

ps:本文来自“Java 笔记虾” 公众号，本人转载

代码如下：

long start = System.currentTimeMillis();
// some code
long finish = System.currentTimeMillis();
long timeElapsed = finish - start;

代码如下：

long start = System.nanoTime();
// some code
long finish = System.nanoTime();
long timeElapsed = finish - start;

代码如下：

Instant start = Instant.now();
// some code       
Instant finish = Instant.now();
long timeElapsed = Duration.between(start, finish).toMillis();

首先，在pom.xml中添加如下依赖：

    org.apache.commons
    commons-lang3
    3.7

代码如下：

import org.springframework.util.StopWatch;
 
StopWatch watch = new StopWatch();
watch.start("watcher");
 
//some code
 
watch.stop();
System.out.println(watch.prettyPrint());