Invalid escape sequence for Regular Expression

Question

Invalid escape sequence (valid ones are \b \t \n \f \r \" \' \ )

public static final boolean isValidPhoneNumber(CharSequence target) {

    if (target == null || TextUtils.isEmpty(target)) {
        Pattern numberPattern = Pattern.compile("^((\+){0,1}91(\s){0,1}(\-){0,1}(\s){0,1})?([0-9]{10})$");
        Matcher numberMatcher = numberPattern.matcher(target);
        return numberMatcher.matches();
    }

    return false;
}

I used a regular expression checked online was working fine but not working on my android application. Plz help...

Answer 1

Your backslashes need to be escaped --

Pattern numberPattern = Pattern.compile("^((\\+){0,1}91(\\s){0,1}(\\-){0,1}(\\s){0,1})?([0-9]{10})$");

this is because Java using the \ character as an escape character, to tell it you really mean \ and not an escape character, you have to write \\.