code: public int getDayOfYear() {
  
          switch (this.month) {
              case 1:
                  return this.dayOfMonth;
              case 2:
                  return 31 + this.dayOfMonth;
              default:
                  return (
                      DAY_OF_YEAR_PER_MONTH[this.month - 2]
                      + this.dayOfMonth
                      + (GregorianMath.isLeapYear(this.year) ? 1 : 0));
          }
  
      }
docs: /*[deutsch]
  <p>Liefert den Tag des Jahres. </p>
  
  @return  int
  @since   3.13/4.10