Andrew Haley wrote:
Ian Rogers wrote:
please give your comments on the attached patch. It tries to reduce the
size of char[] for strings used to hold numbers. It changes Float/Double
equals to use bit based comparisons rather than division. It increases
the use of valueOf methods. It adds a cache of values from -128 to 127
for Long. It adds a cache of the values of zero and one to Float and
Double.
The string size is an estimate. For decimal numbers it will divide the
value repeatedly by 8, causing the string length to be over estimated by
a character for values like 999. This string size is still better than
the current estimate of 33 characters. It also avoids the use of
division (shifts are used) and/or lookup tables.
I am really not convinced by the cache of values from -128 to 127. It's
a significant overhead for the startup time, and I find it hard to imagine
a justification for it.
Andrew.
Sorry, I replied to this off-list accidentally. One alternative is to
move the class initialization into an inner class by placing the cache
in an inner class. That way the cache is only built when valueOf a
cached value is called. This approach would prompt similar changes in
the other Number valueOf methods.
Ian
--
http://www.cs.man.ac.uk/~irogers/
