--- Thomas Singer <email@hidden> wrote:
Integer, Double and so on all are immutable, so you
can safely put them in a
hash map and retrieve them later. If you need
mutable objects for better
memory management (you know "don't optimize before
you really have a
performance problem"?), you are free to write your
own classes with the
methods best suiting your needs.
Thanks for the replies. It seems somewhat strange to
me that without more compelling reasons that no
mutable alternatives have been provided. I know that
since 1.3 there are mutable classes that are package
private to BigInteger.
I am currently considering alternative performance
approaches for some crypto code. So it's sort of the
point of the exercise. I have seen, and measured,
where replacing a single BigInteger instantiation with
a constant results in memory improvements.
The code is highly iterative.
In another case, of three choices for a particular
algorithm, the one where I eliminated BigInteger
(extracted the byte[] from a BigInteger and performed
simple manipulations like shift and add, subtract
against that), was both the fastest and used the least
memory. One of the others was a BigInteger version of
the same algorithm, 2nd fastest, worst memory (did
-Xloggc and counted gc's performed).
But, I didn't want to keep up efforts in avoiding
BigInteger only to later have someone say, but we must
have immutable for such and such compelling reason.
The reasons I have heard are good but not completely
compelling, so I guess I'll keep tinkering away to see
if sometimes avoiding it can result in any substantial
performance gains, thanks.
Mike Hall
