validation - What is the best way for converting phone numbers into international format (E.164) using Java?

Question

What is the best way for converting phone numbers into international format (E.164) using Java?

Given a 'phone number' and a country id (let's say an ISO country code), I would like to convert it into a standard E.164 international format phone number.

I am sure I can do it by hand quite easily - but I would not be sure it would work correctly in all situations.

Which Java framework/library/utility would you recommend to accomplish this?

P.S. The 'phone number' could be anything identifiable by the general public - such as

* (510) 786-0404
* 1-800-GOT-MILK
* +44-(0)800-7310658

that last one is my favourite - it is how some people write their number in the UK and means that you should either use the +44 or you should use the 0.

The E.164 format number should be all numeric, and use the full international country code (e.g.+44)

Answer 1

Google provides a library for working with phone numbers. The same one they use for Android

http://code.google.com/p/libphonenumber/

String swissNumberStr = "044 668 18 00"
PhoneNumberUtil phoneUtil = PhoneNumberUtil.getInstance();
try {
  PhoneNumber swissNumberProto = phoneUtil.parse(swissNumberStr, "CH");
} catch (NumberParseException e) {
  System.err.println("NumberParseException was thrown: " + e.toString());
}

// Produces "+41 44 668 18 00"
System.out.println(phoneUtil.format(swissNumberProto, PhoneNumberFormat.INTERNATIONAL));
// Produces "044 668 18 00"
System.out.println(phoneUtil.format(swissNumberProto, PhoneNumberFormat.NATIONAL));
// Produces "+41446681800"
System.out.println(phoneUtil.format(swissNumberProto, PhoneNumberFormat.E164));