[android] Extract code country from phone number [libphonenumber]

I have a string like this : +33123456789 (french phone number). I want to extract the country code (+33) without knowing the country. For example, it should work if i have another phone from another country. I use the google library https://code.google.com/p/libphonenumber/.

If I know the country, it is cool I can find the country code :

PhoneNumberUtil phoneUtil = PhoneNumberUtil.getInstance();
int countryCode = phoneUtil.getCountryCodeForRegion(locale.getCountry());

but I don't find a way to parse a string without to know the country.

Use a try catch block like below:

try { 

const phoneNumber = this.phoneUtil.parseAndKeepRawInput(value, this.countryCode);

}catch(e){}

In here you can save the phone number as international formatted phone number

internationalFormatPhoneNumber = phoneUtil.format(givenPhoneNumber, PhoneNumberFormat.INTERNATIONAL);

it return the phone number as International format +94 71 560 4888

so now I have get country code as this

String countryCode = internationalFormatPhoneNumber.substring(0,internationalFormatPhoneNumber.indexOf('')).replace('+', ' ').trim();

Hope this will help you

Here's a an answer how to find country calling code without using third-party libraries (as real developer does):

Get list of all available country codes, Wikipedia can help here: https://en.wikipedia.org/wiki/List_of_country_calling_codes

Parse data in a tree structure where each digit is a branch.

Traverse your tree digit by digit until you are at the last branch - that's your country code.

If the string containing the phone number will always start this way (+33 or another country code) you should use regex to parse and get the country code and then use the library to get the country associated to the number.

I have got kept a handy helper method to take care of this based on one answer posted above:

Imports:

import com.google.i18n.phonenumbers.NumberParseException
import com.google.i18n.phonenumbers.PhoneNumberUtil

Function:

    fun parseCountryCode( phoneNumberStr: String?): String {
        val phoneUtil = PhoneNumberUtil.getInstance()
        return try {
            // phone must begin with '+'
            val numberProto = phoneUtil.parse(phoneNumberStr, "")
            numberProto.countryCode.toString()
        } catch (e: NumberParseException) {
            ""
        }
    }

Here is a solution to get the country based on an international phone number without using the Google library.

Let me explain first why it is so difficult to figure out the country. The country code of few countries is 1 digit, 2, 3 or 4 digits. That would be simple enough. But the country code 1 is not just used for US, but also for Canada and some smaller places:

1339 USA
1340 Virgin Islands (Caribbean Islands)
1341 USA
1342 not used
1343 Canada

Digits 2..4 decide, if it is US or Canada or ... There is no easy way to figure out the country, like the first xxx are Canada, the rest US.

For my code, I defined a class which holds information for ever digit:

public class DigitInfo {
  public char Digit;
  public Country? Country;
  public DigitInfo?[]? Digits;
}

A first array holds the DigitInfos for the first digit in the number. The second digit is used as an index into DigitInfo.Digits. One travels down that Digits chain, until Digits is empty. If Country is defined (i.e. not null) that value gets returned, otherwise any Country defined earlier gets returned:

country code 1: byPhone[1].Country is US  
country code 1236: byPhone[1].Digits[2].Digits[3].Digits[6].Country is Canada  
country code 1235: byPhone[1].Digits[2].Digits[3].Digits[5].Country is null. Since   
                   byPhone[1].Country is US, also 1235 is US, because no other   
                   country was found in the later digits

Here is the method which returns the country based on the phone number:

/// <summary>
/// Returns the Country based on an international dialing code.
/// </summary>
public static Country? GetCountry(ReadOnlySpan<char> phoneNumber) {
  if (phoneNumber.Length==0) return null;

  var isFirstDigit = true;
  DigitInfo? digitInfo = null;
  Country? country = null;
  foreach (var digitChar in phoneNumber) {
    var digitIndex = digitChar - '0';
    if (isFirstDigit) {
      isFirstDigit = false;
      digitInfo = ByPhone[digitIndex];
    } else {
      if (digitInfo!.Digits is null) return country;

      digitInfo = digitInfo.Digits[digitIndex];
    }
    if (digitInfo is null) return country;

    country = digitInfo.Country??country;
  }
  return country;
}

The rest of the code (digitInfos for every country of the world, test code, ...) is too big to be posted here, but it can be found on Github: https://github.com/PeterHuberSg/WpfWindowsLib/blob/master/WpfWindowsLib/CountryCode.cs

The code is part of a WPF TextBox and the library contains also other controls for email addresses, etc. A more detailed description is on CodeProject: International Phone Number Validation Explained in Detail