time to execute a java app

[svpranay]

Hi,
I would like to find the total time taken by my java program. Is there any way i could do it through eclipse ?

[Norm]

Do you want to include any overhead caused by eclipse?
Do you want to include the time to load the JVM?
What kind of app is it?

[berkeleybross]

Not sure what your asking.

You could call System.getNanoTime() and assign it to some long variable at startup,
then when the program is closing
System.out.println (System.getNanoTime() - startTime);

would give you the run time in nanoseconds (approximately).

Why is it important?

[berkeleybross]

Apologies, it should be "System.nanoTime();"

[Eranga]

Hi,
I would like to find the total time taken by my java program. Is there any way i could do it through eclipse ?

Or, do you want to find total execution time of your application?

[svpranay]

Hi,
I just wanted to calculate the time taken to execute a piece of code.So i guess System.nanoTime() would work.

Thanks for all of you.

[JosAH]

Hi,
I just wanted to calculate the time taken to execute a piece of code.So i guess System.nanoTime() would work.

Thanks for all of you.

You are going to be bitten by the JIT compiler if you don't pay any attention; at first a piece of code is interpreted until the HotSpot mechanism hits: then it is going to be compiled and real machine code is running. Allow your code to 'warm up' and only then set your timers; if you want to time, say, a method P(), do this:

// allow the HotSpot mechanism to do it's deeds
for (int i= 0; i < 100000; i++)
   P();
long start= System.nanoTime();
for (int i= 0; i < 100000; i++)
   P();
long t= (System.nanoTime()-start)/100000;

The second loop takes the average runtime just to stabilize the measurements.

kind regards,

Jos