code: private StringBuffer format(Date date, StringBuffer toAppendTo,
                                  FieldDelegate delegate) {
          // Convert input date to time field list
          calendar.setTime(date);
  
          boolean useDateFormatSymbols = useDateFormatSymbols();
  
          for (int i = 0; i < compiledPattern.length; ) {
              int tag = compiledPattern[i] >>> 8;
              int count = compiledPattern[i++] & 0xff;
              if (count == 255) {
                  count = compiledPattern[i++] << 16;
                  count |= compiledPattern[i++];
              }
  
              switch (tag) {
              case TAG_QUOTE_ASCII_CHAR:
                  toAppendTo.append((char)count);
                  break;
  
              case TAG_QUOTE_CHARS:
                  toAppendTo.append(compiledPattern, i, count);
                  i += count;
                  break;
  
              default:
                  subFormat(tag, count, delegate, toAppendTo, useDateFormatSymbols);
                  break;
              }
          }
          return toAppendTo;
      }
docs: Called from Format after creating a FieldDelegate