code: protected final void parseFileNamePattern() {
      List converters = new ArrayList();
      List fields = new ArrayList();
  
      ExtrasPatternParser.parse(
              fileNamePatternStr, converters, fields, null,
              ExtrasPatternParser.getFileNamePatternRules());
      patternConverters = new PatternConverter[converters.size()];
      patternConverters =
        (PatternConverter[]) converters.toArray(patternConverters);
      patternFields = new ExtrasFormattingInfo[converters.size()];
      patternFields = (ExtrasFormattingInfo[]) fields.toArray(patternFields);
    }
docs: Parse file name pattern.