GNU classpath from ikvm 0.24.0.1 A regular expression with a zero-width positive lookbehind does not compile: Pattern x = Pattern.compile("(?<=X)") ; It seems that lookbehind isn't supported by the regex implementation. Similarly, zero-width negative lookbehind "(?<!X)" Andy
This bug is the same as Bug #25812, and it has been fixed. As far as I know, IKVM uses a precompiled GNU Classpath library. But this fix was done only recently, and it is not reflected in IKVM. *** This bug has been marked as a duplicate of 25812 ***