Cant get this regex to work, please help

Question

Hey, its that regex time again:
i need a regex that matches a string that:
has any text followed by
has the following substring: navRelId/1000.1001 followed by
any text followed by
not the following substring: resource_type_category_id/2 followed by
any text
here is an example of a string that should NOT match this regex because it has resource_type_category_id/2 AND navRelId/1000.1001
http://localhost:8080/MedicalArea.bsci/,,/navRelId/1000.1001/method/MEDICAL_AREA_RESOURCES_CATEGORY/id/10067361/resource_type_category_id/1/resource_type_id/0/cid/7/seo.serve
here is an example of a string that SHOULD match this regex because it has
resource_type_category_id/1 AND navRelId/1000.1001
http://localhost:8080/MedicalArea.bsci/,,/navRelId/1000.1001/method/MEDICAL_AREA_RESOURCES_CATEGORY/id/10067361/resource_type_category_id/2/resource_type_id/0/cid/7/seo.serve
ive tried the following regex and it doesnt work:
//the goal is to have the find() return false -
public TestSearch(){
Pattern p = Pattern.compile("(?i).*?navRelId[/=]1000\\.1001.*?(?!resource_type_category_id[=/]2).*?");
Matcher m = p.matcher("http://localhost:8080/MedicalArea.bsci/,,/navRelId/1000.1001/method/MEDICAL_AREA_RESOURCES_CATEGORY/id/10067361/resource_type_category_id/2/resource_type_id/0/cid/7/seo.serve");
if(m.find()){
System.out.println("Match found!");
} else {
System.out.println("poop!"); //we want this!
}This is a pure regex question, so dont tell me to use String.indexOf(), i cant do that, i need to do this with one regex.
Thanks!

Answer 1

Because you used a reluctant quantifier in ".*?", the negative lookahead gets applied immediately after "navRelId/1000.1001" is matched. And it immediately succeeds because the "resource_type_etc." substring doesn't appear until later. After that, the final ".*?" is free to match the rest of the string (but doesn't actually match anything; see below for the reason why).
Lookaheads are slippery; you have to be careful and make sure that (1) they get applied at the right position, and (2) they don't match to much or too little. I accomplished the first goal by making sure the lookahead is always and only applied right after a slash, and the second by anchoring the regex to the "/seo.serve" at the end of the URL.
By the way, you should never use a reluctant quantifier at the end of a regex. If you're using the matches() method to apply the regex, making the quantifier reluctant has no effect except maybe to slow down the match slightly. If you use find() or lookingAt(), the quantifier will always match the minimum number of times allowed, which is zero in this case.