I am parsing a .txt, line by line, with considering a target token. I use a regex processor engine.
I match each line against:
"(^|.*[\\s])"+token+"([\\s].*|$)"
where token is a string. When:
token="6-7(3-7"
it arises the following exception:
Exception in thread "main" java.util.regex.PatternSyntaxException:
Unclosed group near index 27
(^|.*[\s])6-7(3-7([\s].*|$)
How can I solve this?
You have special characters in your token.
Have a look at Pattern.quote():
public static String quote(String s)
Returns a literal pattern String for the specified String.
This method produces a String that can be used to create a Pattern that would match the string s as if it were a literal pattern.
Metacharacters or escape sequences in the input sequence will be given no special meaning.
This should do the trick for you:
String pattern = "(^|.*[\\s])" + Pattern.quote(token) + "([\\s].*|$)";
No need for doing the string magic yourself! :-)
You should make sure to escape special characters in any plain-text string you use to make regex patterns. Replace "(" with "\(", and similarly for bare backslashes (before any other steps), periods, and all other special characters, at least all those you expect to see in the input. (If it's arbitrary input from users, assume every character will be included.)
(in6-7(3-7. You probably want to escape it:6-7\\(3-7