Though regex support in Java was introduced several years ago (but not that many: JDK 1.4 AFAIK, 2002 circa, if we mean the java.util.regex package), it still doesn't offer advanced things such as match-time code evaluation, match-time pattern interpolation and conditional interpolation.
So, for example, with a Java regex you can't build a recursive pattern (to check for instance if the parentheses in a text are balanced), while in Perl you can ;-)
Update
It can also be interesting to see how more verbose Java regexes are compared to Perl regexes.
Here is a simple Perl example:
my $pat = qr/a+b/;
my $res = "aaab" =~ $pat;
and here is its Java counterpart:
import java.util.regex.*;
Pattern pat = Pattern.compile("a+b");
Matcher mat = pat.matcher("aaab");
boolean res = mat.matches();
Really, the above 2 last lines could be substituted by the following somewhat shorter code:
boolean res = pat.matcher("aaab").matches();
but if you don't explicitly instantiate a Matcher object, you can't have several things such as match, prematch, postmatch etc. which Perl gives you for free (through the various predefined variables $&, $`, $' etc.)
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Java has had regular expressions for years. They've even implemented the named capture syntax that we won't have until perl6.
I didn't think they were as flexible as the Perl ones (e.g. using composition to build up regexes from component regexes, //e, etc.)?
However I freely admit I could be wrong. It's been several years since I've done any serious Java and I'm too lazy to look things up :-)
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