Regex Matching bigger String first

Question

I am trying to match this string:

www.abcdgbs.com/p/Flights/abcd

with regex

regex = ".*(/Hotels|(/p)?/Flights).*";

pipe separated for matching from multiple regex

I want to get the index where this string is matching (15 in above case) my code is

String test = "www.abcdgbs.com/p/Flights/abcd";
String regex = ".*(/Hotels|(/p)?/Flights).*";
Pattern patt = Pattern.compile(regex);
Matcher m = patt.matcher(test);
System.out.println(m.find() ? m.start(1) : -1);

It is ignoring /p and matching from Flights giving me index as 17, I want this to first match with bigger string ie /p/Flights first and give index as 15.

I want to use same regex for matching www.abcdgbs.com/Flights/abcd as well.

Answer 1

Remove .* from your regex and match the text that you want:

String regex = "(/Hotels|(/p)?/Flights)";

With greedy .* in your regex before these keywords, regex engine is attempting to match longest string before any of those keywords as your (/p)? is optional.

So with .* your first captured group is /Flights but with .* removed your first captured group is /p/Flights .

You will get 15 printed now.

Answer 2

Here is my extended version:

(?:(?:(?P<PROTOCOL>https?):)?//)?(?P<DOMAIN>.+?)/(?P<PREFIX>p/)?(?P<TYPE>Flights|Hotels)(?P<SUFFIX>/.+)?

See in colors here: https://regex101.com/r/wD7aR7/2