Regex with -, ::, ( and )

Question

I need to split the string

(age-is-25::OR::last_name-is-qa6)::AND::(age-is-20::OR::first_name-contains-test)

into

string[0] = (age-is-25::OR::last_name-is-qa6)

string[1] = AND

string[2] = (age-is-20::OR::first_name-contains-test)

I tried writing so many regex expressions, but nothing works as expected.

Using the following regex, Matcher.groupCount() which returns 2 but assigning results to an arraylist returns null as the elements.

Pattern pattern = Pattern.compile("(\\)::)?|(::\\()?");

I tried to split it using ):: or ::(.

I know the regex looks too stupid, but being a beginner this is the best I could write.

Answer 1

You can use positive lookahead and lookbehind to match the first and last parentheses.

String str = "(age-is-25::OR::last_name-is-qa6)::AND::(age-is-20::OR::first_name-contains-test)";  for (String s : str.split("(?<=\\))::|::(?=\\()"))     System.out.println(s); 

Outputs:

(age-is-25::OR::last_name-is-qa6) AND (age-is-20::OR::first_name-contains-test) 

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Just a note however: It seems like you are parsing some kind of recursive language. Regular expressions are not good at doing this. If you are doing advanced parsing I would recommend you to look at other parsing methods.

Answer 2

To me it looks like a big part of your stress comes from the need for escaping special characters in your search term. I highly recommend to not do manual escaping of special characters, but instead to use Pattern.quote(...) for the escaping.