How do I time a method's execution in Java?

Question

1. How do I get a method\'s execution time?
2. Is there a Timer utility class for things like timing how long a task takes, etc?

Mos

Answer 1

Spring provides a utility class org.springframework.util.StopWatch, as per JavaDoc:

Simple stop watch, allowing for timing of a number of tasks, exposing total running time and running time for each named task.

Usage:

StopWatch stopWatch = new StopWatch("Performance Test Result");

stopWatch.start("Method 1");
doSomething1();//method to test
stopWatch.stop();

stopWatch.start("Method 2");
doSomething2();//method to test
stopWatch.stop();

System.out.println(stopWatch.prettyPrint());

Output:

StopWatch 'Performance Test Result': running time (millis) = 12829
-----------------------------------------
ms     %     Task name
-----------------------------------------
11907  036%  Method 1
00922  064%  Method 2

With Aspects:

@Around("execution(* my.package..*.*(..))")
public Object logTime(ProceedingJoinPoint joinPoint) throws Throwable {
    StopWatch stopWatch = new StopWatch();
    stopWatch.start();
    Object retVal = joinPoint.proceed();
    stopWatch.stop();
    log.info(" execution time: " + stopWatch.getTotalTimeMillis() + " ms");
    return retVal;
}