regular expression for finding string between [[ ]] and {{}}

Question

How could I find string between [[ ]]? After searching a answer I find this method below, but I cannot find the regular expression for [[ ]], neither for {{ }}.

What I want to do is to find e.g. [[abc]]XXXXXXXXXX[[def]], and save abc, def as a ArrayList.

String s = "[[abc]]XXXXXXXXXX[[def]]";
Pattern p = Pattern.compile("[[(.*?)]]")
Matcher m = p.matcher(s);
if (m.find()) {
    System.out.println(m.group(i)); // => "abc","def"
}

You'll need to escape the `[` since they're regex special characters. — Amber, Aug 18 '13 at 18:11
What should be result for this kind of data `{{a[[b]]e}}`, `[[a{{b}}c]]`? Or maybe this kind of input is impossible? — Pshemo, Aug 18 '13 at 18:19
{{a[[b]]e}}, [[a{{b}}c]] is impossible. If [[]] is not easy to express in regex, how about {{}}? any ideas? — user2694404, Aug 18 '13 at 19:04

score 4 · Accepted Answer · edited May 23 '17 at 12:15

4

You must double escape the opening square brackets (you can do the same with the closing) since they are used to define character classes:

Pattern p = Pattern.compile("\\[\\[(.*?)]]");

(exactly the same with curly braces, that are used for quantifiers)

You can read this fabulous post about the incredible world of square brackets.

edited May 23 '17 at 12:15

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answered Aug 18 '13 at 18:17

Casimir et Hippolyte

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regular expression for finding string between [[ ]] and {{}}

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