code: @Override
      public void readExternal(ObjectInput in)
          throws IOException, ClassNotFoundException {
  
          byte header = in.readByte();
  
          switch (header) {
              case HIJRI:
                  this.obj = this.readHijri(in);
                  break;
              case PERSIAN:
                  this.obj = this.readPersian(in);
                  break;
              case COPTIC:
                  this.obj = this.readCoptic(in);
                  break;
              case ETHIOPIAN_DATE:
                  this.obj = this.readEthiopianDate(in);
                  break;
              case ETHIOPIAN_TIME:
                  this.obj = this.readEthiopianTime(in);
                  break;
              case MINGUO:
                  this.obj = this.readMinguo(in);
                  break;
              case JULIAN:
                  this.obj = this.readJulian(in);
                  break;
              case THAI_SOLAR:
                  this.obj = this.readThaiSolar(in);
                  break;
              case JAPANESE:
                  this.obj = this.readJapanese(in);
                  break;
              case INDIAN:
                  this.obj = this.readIndian(in);
                  break;
              case HISTORIC:
                  this.obj = this.readHistoric(in);
                  break;
              case HEBREW_DATE:
                  this.obj = this.readHebrewDate(in);
                  break;
              case HEBREW_TIME:
                  this.obj = this.readHebrewTime(in);
                  break;
              case CHINESE:
                  this.obj = this.readChinese(in);
                  break;
              case KOREAN:
                  this.obj = this.readKorean(in);
                  break;
              case VIETNAMESE:
                  this.obj = this.readVietnamese(in);
                  break;
              case JUCHE:
                  this.obj = this.readJuche(in);
                  break;
              default:
                  throw new InvalidObjectException("Unknown calendar type.");
          }
  
      }
docs: /*[deutsch]
  <p>Implementierungsmethode des Interface {@link Externalizable}. </p>
  
  @param   in      input stream
  @throws  IOException in any case of IO-failures
  @throws  ClassNotFoundException if class loading fails