code: private static int toContext(int style) {
          switch (style) {
              case Calendar.SHORT_FORMAT:
              case Calendar.NARROW_FORMAT:
              case Calendar.LONG_FORMAT:
                  return DateFormatSymbols.FORMAT;
              case Calendar.SHORT_STANDALONE:
              case Calendar.NARROW_STANDALONE:
              case Calendar.LONG_STANDALONE:
                  return DateFormatSymbols.STANDALONE;
              default:
                  throw new IllegalArgumentException("Invalid style: " + style);
          }
      }
docs: Transform a {@link Calendar} style constant into an ICU context value.