inputDigit method
Formats a phone number on-the-fly as each digit is entered.
nextChar
the most recently entered digit of a phone number.
Formatting characters are allowed, but as soon as they are encountered
this method formats the number as entered and not 'as you type' anymore.
Full width digits and Arabic-indic digits are allowed, and will be shown
as they are.
returns the partially formatted phone number.
Implementation
String inputDigit(String nextChar) {
_currentOutput = _inputDigitWithOptionToRememberPosition(nextChar, false);
return _currentOutput;
}