Measure execution time for a Java method [duplicat

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This question already has answers here:

How do I time a method's execution in Java? (38 answers)

Closed 6 years ago.

How do I calculate the time taken for the execution of a method in Java?

Answer 1

Check this: System.currentTimeMillis.

With this you can calculate the time of your method by doing:

long start = System.currentTimeMillis();
class.method();
long time = System.currentTimeMillis() - start;

Answer 2

To be more precise, I would use nanoTime() method rather than currentTimeMillis():

long startTime = System.nanoTime();
myCall(); 
long stopTime = System.nanoTime();
System.out.println(stopTime - startTime);

In Java 8 (output format is ISO-8601):

Instant start = Instant.now();
Thread.sleep(63553);
Instant end = Instant.now();
System.out.println(Duration.between(start, end)); // prints PT1M3.553S

Guava Stopwatch:

Stopwatch stopwatch = Stopwatch.createStarted();
myCall();
stopwatch.stop(); // optional
System.out.println("Time elapsed: "+ stopwatch.elapsed(TimeUnit.MILLISECONDS));

Answer 3

In case you develop applications for Android you should try out the TimingLogger class.
Take a look at these articles describing the usage of the TimingLogger helper class:

• Measuring performance in the Android SDK (27.09.2010)
• Discovering the Android API - Part 1 (03.01.2017)

Answer 4

Nanotime is in fact not even good for elapsed time because it drifts away signficantly more than currentTimeMillis. Furthermore nanotime tends to provide excessive precision at the expense of accuracy. It is therefore highly inconsistent,and needs refinement.

For any time measuring process,currentTimeMillis (though almost as bad), does better in terms of balancing accuracy and precision.

Answer 5

If you are currently writing the application, than the answer is to use System.currentTimeMillis or System.nanoTime serve the purpose as pointed by people above.

But if you have already written the code, and you don't want to change it its better to use Spring's method interceptors. So for instance your service is :

public class MyService { 
    public void doSomething() {
        for (int i = 1; i < 10000; i++) {
            System.out.println("i=" + i);
        }
    }
}

To avoid changing the service, you can write your own method interceptor:

public class ServiceMethodInterceptor implements MethodInterceptor {
    public Object invoke(MethodInvocation methodInvocation) throws Throwable {
        long startTime = System.currentTimeMillis();
        Object result = methodInvocation.proceed();
        long duration = System.currentTimeMillis() - startTime;
        Method method = methodInvocation.getMethod();
        String methodName = method.getDeclaringClass().getName() + "." + method.getName();
        System.out.println("Method '" + methodName + "' took " + duration + " milliseconds to run");
        return null;
    }
}

Also there are open source APIs available for Java, e.g. BTrace. or Netbeans profiler as suggested above by @bakkal and @Saikikos. Thanks.

Answer 6

You might want to think about aspect-oriented programming. You don't want to litter your code with timings. You want to be able to turn them off and on declaratively.

If you use Spring, take a look at their MethodInterceptor class.