code: public static boolean isValid(
          int year,
          int month,
          int dayOfMonth
      ) {
  
          return (
              (year >= 1) && (year <= MAX_YEAR)
              && (month >= 1) && (month <= 12)
              && (dayOfMonth >= 1) && (dayOfMonth <= 30));
  
      }
docs: /*[deutsch]
  <p>Pr&uuml;ft, ob die angegebenen Parameter ein wohldefiniertes Kalenderdatum beschreiben. </p>
  
  @param   year        the year of era to be checked
  @param   month       the month to be checked
  @param   dayOfMonth  the day of month to be checked
  @return  {@code true} if valid else  {@code false}
  @see     #of(int, int, int)
  @since   3.34/4.29