I frequent wrap code in a System.nanoTime() pair in order to timing it. Something like:
long start = System.nanoTime(); methodToBeTimed(); long elapsedTime = System.nanoTime() - start; There is any good timing library that helps with this problem? Also homegrown code will be accepted.
NB
A profiler is not a solution here, since I want to enforce some time constraints in my unit tests, so I want to timing methods programmatically.
Ignore this answer as the project is no longer active
I haven't used it but I came across perf4j recently.
Not a direct answer to your question, but I am also often using this tip to time my code and just wrote the following simple Eclipse -> Surround With template:
long startTime = System.currentTimeMillis(); ${line_selection}${cursor} long totalTime = System.currentTimeMillis() - startTime; System.out.println("Total time = " + totalTime); System.out.println(); 
JUnit 4 got a built-in timing-contraint functionality.
@Test(timeout=X)
should do the trick. X is the maximum number of milliseconds the method is allowed to run.
there is StopWatch from commons-lang, it also allows you to split timer.
JETM is a good library for doing this. It can also provide with mins, maxs and averages, plus can generate informative graphs.
Tried JPerf ?
What kind of help are you looking for with this problem? You have the basics in place. You get the elapsed time in Nanoseconds, accurate to whatever resolution the underlying OS/Hardware is capable of.
Also... and I know you said no profilers... but I have had outstanding experience with YourKit. It provides an API that you can use to control profiling from the outside. Depending on what your exact problem is, this one might be worth having a look at.
And in addition to reading the wikis on that site, i recommend reading:
I've just started using Java Simon (formerly on Google Code), and it seems awesome! A simple set of stopwatches and counters with few dependencies.
A simple wrapper for commons-lang StopWatch which take into account multi threading environment, when stop is not invoked leap stat is not counted and 'failed leaps count' incremented (you may not include stop in finally block if the behavior is desired), exposes live statistic via JMX and deliver consolidated serializable result over the network. Example usage:
private PerfStat methodPerf = new PerfStat("method.under.test"); ... public void myMethod() { methodPerf.start(); ... long timeNs = methodPerf.stop(); } dependency
<dependency> <groupId>org.droolsassert</groupId> <artifactId>da-utils</artifactId> </dependency> 
minLapTime would work, since it is initialized with the lowest possible value: 0. It should probably be initialized with (and reset to) Long.MAX_VALUE.