Java, escaping (using) quotes in a regex

Question

I\'m trying to use the following regex in Java, that\'s supposed to match any lang=\"2-char-lang-name\":

String lang = \"lang=\\\"\" + L.detectL         


        

Answer 1

Have you tried it with a single backslash? The output of

public static void main(String[] args) {
  String inputString = "";
  System.out.println(inputString.replaceFirst("lang=\"[^\"]*\"", "lang=\"American\"" ));
}

is

which, if I'm reading you correctly, is what you want.

EDIT to add: the reason a single backslash works is that it's not actually part of the string, it's just part of the syntax for expressing the string. The length of the string "\"" is 1, not 2, and the method replaceFirst just sees a string containing a " (with no backslash). This is why e.g. \s (the whitespace character class in a regex) has to be written \\s in a Java string literal.

On the wisdom of using regex: this should be fine, if you're sure about the format of the files you're processing. If the files might include a commented-out header complete with lang spec above the real header, you could be in trouble!