Michael Nascimento Santos's Blog

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Playing with the Tiger: Measuring nanos

Ok, sorry for not blogging for so long, but I have to work, date etc. :-D

I hope this is the start of a series of small, but informative blog entries about new features available in Tiger, especially the ones a hundred people haven't mentioned before me :-D

To begin with, I'll show you how to use the new nanoTime() method in System. An important thing to notice is that nanoTime()'s return and currentTimeMillis's are not necessarily related to each other - meaning they don't have to use the same reference to zero. This example also uses the new static import feature. I am not saying I like it or not. That's what I expect you to say.

Here's the code:

import static java.lang.System.*;

public class Nano {
   public static void main(String[] args) {
      long time = 0;
      long newTime;
      long smaller = 9999999999999L;

      for (int i = 0; i < 100000; i++) {
         time = nanoTime();
         newTime = nanoTime();

         smaller = Math.min(smaller, newTime - time);
      }

      out.println("Smallest nano interval measured: " + smaller);
      out.println("Current time millis: " + currentTimeMillis());
      out.println("Nano time: " + nanoTime());
   }
}

Save it in Nano.java and compile it with:

javac -source 1.5 Nano.java

Then run it normally with:

java -cp . Nano

My results (P4, 1GB RAM, Windows 2000 Pro) are:

Smallest nano interval measured: 1116
Current time millis: 1076038988125
Nano time: 8736336585045

This method is intended to be used as a way to measure performance, for instance. Here, I just tried to get its precision in my current box configuration.

Please let me know if you get smallest nano intervals in your platform/configuration. See you soon ;-)

BREAKING NEWS: Got Tiger?

I was going to blog about Date and Calendar (and how terrible they are), but these must wait now.

Straight to the point: if you want to get J2SDK 1.5.0 alpha, just go to:

http://www.javalobby.org/members/j2se15.jsp

This is a cooperation between JavaLobby - hey, just became a member 3 weeks ago, after years of Java, can you believe it? - and Sun. This is really a private release, so, you are not allowed to share your opinions about it with anyone except Sun. No, no feedback on this blog or any comments about J2SDK 1.5 alpha are allowed at all. You must be a member of JavaLobby to download it.

Are you still reading this??? Go there and download it now!

This work is licensed under a Creative Commons License.