Le 13/08/2009 03:30, Martin Buchholz a écrit :
Hi regex/String team,
We would like to contribute a performance improvement for Matcher.
Just a minor comment, there is not @since 1.7
Rémi
Please file a bug.
category: java_util_regex
Synopsis: Faster Matcher by replacing StringBuffer with StringBuilder
Description:
The old Matcher API and implementation depend on the old StringBuffer class.
The use of StringBuilder gives measurable performance improvement in
real world applications.
http://cr.openjdk.java.net/~martin/webrevs/openjdk7/Matcher-perf/
Written by Jeremy Manson.
Here's a microbenchmark, where it gives 25% win:
public class StringReplace {
static String jabber = "Twas brillig, and the slithy toves " +
"Did gyre and gimble in the wabe; " +
"All mimsy were the borogoves, " +
"And the mome raths outgrabe. " +
" " +
"Beware the Jabberwock, my son! " +
"The jaws that bite, the claws that catch! " +
"Beware the Jubjub bird, and shun " +
"The frumious Bandersnatch!" +
" " +
"He took his vorpal sword in hand: " +
"Long time the manxome foe he sought— " +
"So rested he by the Tumtum tree, " +
"And stood awhile in thought. " +
" " +
"And as in uffish thought he stood, " +
"The Jabberwock, with eyes of flame, " +
"Came whiffling through the tulgey wood, " +
"And burbled as it came! " +
" " +
"One, two! One, two! and through and through " +
"The vorpal blade went snicker-snack! " +
"He left it dead, and with its head " +
"He went galumphing back. " +
" " +
"And hast thou slain the Jabberwock? " +
"Come to my arms, my beamish boy! " +
"O frabjous day! Callooh! Callay!" +" " +
"He chortled in his joy. " +
" " +
"'Twas brillig, and the slithy toves " +
"Did gyre and gimble in the wabe; " +
"All mimsy were the borogoves, " +
"And the mome raths outgrabe?";
public static void replace() {
long start = System.currentTimeMillis();
for (int i = 0; i< 100000; i++) {
jabber.replaceAll("the", "ze");
}
long stop = System.currentTimeMillis();
System.out.println(stop);
System.out.println(start);
System.out.println(stop - start);
}
public static void main(String[] args) {
for (int i = 0; i< 5; i++) {
replace();
}
}
}
