Are java.lang classes better served by the JVM?

[Mark Roos]

>From Raffaello
        are java.lang classes better served by the JVM than other classes?
        Here's a small experiment.
        I created a MyInteger class that exposes the very same 
implementation
        of Integer.numberOfTrailingZeros(int), copied verbatim.

We did similar micro benchmarks, using Hanoi as a test case, to see the 
speed variations
the various types of integers would have.  We tried int, long, Long and 
our version of
a boxed long.  One case where we saw a 3-5x difference was between boxed 
and
primitive versions.  This was expected.

The other case was when we compared our custom boxed long with the Java 
Long.
We found the issue here was with the creation and collection of instances. 
The use of
the integer cache made a huge difference.  Once we did that out times 
became very close.
So while there may be internal optimization by the JVM  in the Hanoi case 
it had a minor
effect.

regards
mark
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