Writing a java annotation for timing method call

Question

I want to write a java annotation which times the method call. something like this:

@TimeIt
public int someMethod() { ... }

and when this method is invoked, it should output on console how long this method took

I know how to do it in python, this is what I want it to do:

from time import time, sleep

def time_it(func):
    def wrapper(*args, **kwargs):
        start = time()
        func(*args, **kwargs)
        stop = time()
        print "The function", func.__name__, " took %.3f" % (stop - start)
    wrapper.__name__ = func.__name__
    return wrapper

@time_it
def print_something(*args, **kwargs):
    print "before sleeping"
    print args, kwargs
    sleep(3) # wait 3 seconds
    print "after sleeping"

print_something(1, 2, 3, a="what is this?")

So my questions are? Where do I find some documentation to write something like this, I tried apt documentation, had no luck with it. can someone help with writing something like this?

Answer 1

AFAIK, Tomasz is right in saying that this can't be done using annotations. I think the confusion stems from the fact that Python decorators and Java annotations share the same syntax but are completely different in terms of the behavior they offer!

Annotations are metadata attached to your class/methods/fields. This blog post addresses the point of timing methods using AOP. Though it uses Spring, the basic premise remains the same. If you are good to go with an AOP compiler, it shouldn't be too difficult to translate the code. Another reference (spring specific) here.

EDIT: If your aim is to have a overall method timing for your application without using full blown profilers, you can use hprof for collecting total execution statistics.