addYears method

@override DateTime addYears(DateTime date, int years)

Returns a new DateTime where the year is years from this year and the DateTime.day is equal to dayInYear-1 added to January 1st.

Implementation

@override
DateTime addYears(DateTime date, int years) {
  if (years == 0) return startDate(date);
  var localYears = years;
  var localDate = startDate(date);
  if (localYears.isNegative) {
    while (localYears < 0) {
      localDate = previous(localDate);
      localYears++;
    }
  } else {
    while (localYears > 0) {
      localDate = next(localDate);
      localYears--;
    }
  }
  return localDate;
}