Java Regex Match

Question

Given such Regex code:

Matcher m = Pattern.compile("c:.*?(|t:){1}.*?").matcher(string);

I only want to match something like c:somesubstring|t:somesubstring. However it also matches some thing like this:

c:somesubstring

and

c:somesubstring|a:somesubtring

How could this come? I use (|t:){1} to guarantee that the pattern |t: occurs and occurs only once. Will be helpful to tell me what's wrong with my regex and give me a regex to match only c:somesubstring|t:somesubstring

{1} does not guarantee that the preceding item does not appear more than once. — Biffen
– Biffen, Commented Dec 5, 2014 at 16:55

Avinash Raj · Accepted Answer · 2014-12-05 16:53:32Z

1

| is a special meta character in regex which acts like a logical OR operator usually used to combine two regexes . You need to escape the | symbol, so that it would match a literal | symbol.

Matcher m = Pattern.compile("c:.*?(\\|t:){1}.*?").matcher(string);

much shorter.

Matcher m = Pattern.compile("c:.*?\\|t:.*?").matcher(string);

answered Dec 5, 2014 at 16:53

Avinash Raj

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1 Comment

Avinash Raj Over a year ago

or put | in a char class like [|]

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