java - Regex trying to get some text after text doesn't work -

i got code should retrieve id value url.:

        string xmltag = "http://www.facebook.com/profile.asp?id=123456789";         xmltag = xmltag.replaceall("/", "//");          //regex variables         final string regexurl = "(?:(?:http|https):\\//\\//)?(?:www.)?facebook.com\\//(?:(?:\\w)*#!\\//)?(?:[?\\w\\-]*\\//)?(?:profile.asp\\?id=(?=\\d.*))?([\\w\\-]*)?";         final pattern patternurl = pattern.compile(regexurl);         final matcher matcherurl = patternurl.matcher(xmltag);            string urlresult = matcherurl.group(0);                  system.out.println("group(0) = " + urlresult);         string regexid = "(?<=http:////www.facebook.com//profile.asp?id=).*";         system.out.println("regexid =   " + regexid);          final pattern patternid = pattern.compile(regexid);         final matcher matcherid = patternid.matcher(urlresult);                  system.out.println("id = " + matcherid.matches()); 

the output should be: 123456789 'true' 'atcherid.matches()'

but instead of i'm getting 'false' that:

exception in thread "main" java.lang.illegalstateexception: no match found     @ java.util.regex.matcher.group(unknown source)     @ mainclass.main(mainclass.java:19) 

do miss here ?

if objective find id url, suggest simpler regex instead of using such long one.

sample:

    string xmltag = "http://www.facebook.com/profile.asp?id=123456789";     string regexid = "\\?id=(\\d+)";     final pattern patternid = pattern.compile(regexid);     final matcher matcherid = patternid.matcher(xmltag);     system.out.println("found id = " + matcherid.find());     system.out.println("id = " + matcherid.group(1));