Finding a RegEx subpattern within a pattern

Question

I'm trying to remove the +1 (country code) from a phone number (I'm working on a normalization project). For example, the user has a phone number in the format of +1(703)-555-5787 and he wants it to be (703)-555-5787 (without the +1 at the front).

My theory is that I can search through the phoneNum string based on a regex pattern. Once it is found, I can print it or do whatever I like. My code is seen below:

public static String normalizePrefix(final String phoneNum) {
    String ret = phoneNum;

    if (!phoneNum.contains("+1")) {
        logger.log(Level.INFO, "input phone number doesn't contain country code (+1)");
    }
    else {          

        String regex = "(\\+1)([2-9][0-9][0-9])-([2-9][0-9]{2})-([0-9]{4})";
        Pattern p = Pattern.compile(regex);
        Matcher m = p.matcher(phoneNum); 


            if (phoneNum.matches(regex)){
                ret = m.group().substring(2, m.end());
            }

    }
    logger.log(Level.INFO, phoneNum + "-->" + ret);
    return ret;
}

What am I missing?

Answer 1

matches would try to match the pattern exactly ..

So in case you have phone number in between the string your regex won't work.

use Matcher's find method

 if (m.find())
 {
      ret = m.group().substring(2, m.group().length());
 }

Answer 2

Try the regex :

String regex = "\\([0-9]{3}\\)-[0-9]{3}-[0-9]{4}";

And modify the if block as :

if (m.find()){
            ret = m.group(0);
}

Answer 3

I've tried and tested here the following regular expression:

String regex = "\\([0-9]{3}\\)-[0-9]{3}-[0-9]{4}";

Afterwards, modify the if block:

if (m.matches()){
    ret = m.group(2);
}

This should always return the phone number, no matter if the +1 prefix is there or not.

Answer 4

So, I figured it out (I tried to answer my question about 20 minutes after I asked it but SO wouldn't let me). Nonetheless, thank you all for your feedback and support, I'm truly grateful.

Here was my mistake:

My regex was String regex = "(\\\\+1)([2-9][0-9][0-9])-([2-9][0-9]{2})-([0-9]{4})"; but my phoneNum string was +1(703)-555-4563. It was giving me errors because the regex was looking for a number of this format instead: +1703-555-4563 (without the () around the area code). Thus, finding a substring was impossible because it did not exist. My regex should have been String regex = "(\\\\+1)(\\\\([2-9][0-9][0-9]\\\\))-([2-9][0-9]{2})-([0-9]{4})"; .

Thank you everyone for your help!

Much appreciated :)