Java 정규 기반 날짜 확인 기능의 예

private void checkDate() throws IOException {
    // 4 
    String sep = "[-\\./_]";
    //  
    String strPattern = "^(19[4-9]\\d|20\\d{2})" + sep;
    strPattern += "(";
    //  （1,3,5,7,8,10,12)
    strPattern += "((0?[13578]|1[02])" + sep + "(0?[1-9]|[12][0-9]|3[01]))|";
    //  (4,6,9,11)
    strPattern += "((0?[469]|11)" + sep + "(0?[1-9]|[12][0-9]|30))|";
    //  （2）
    strPattern += "((2)" + sep + "(0?[1-9]|[12]\\d))";
    strPattern += ")$";
    Pattern p = Pattern.compile(strPattern);
    Matcher m = p.matcher("");
    int count = 0;
    String fileName = ExcelGene.class.getResource("date.txt").getFile();
    BufferedReader br = new BufferedReader(new FileReader(fileName));
    String line = null;
    while ((line = br.readLine()) != null) {
      count++;
      if (line.trim().length() > 0) {
        m.reset(line);
        if (!m.find()) {
          System.out.println(count + " " + line);
        } else {
          String year = m.group(1);
          String month = m.group(4);
          month = month == null ? m.group(7) : month;
          month = month == null ? m.group(10) : month;
          String date = m.group(5);
          date = date == null ? m.group(8) : date;
          date = date == null ? m.group(11) : date;
          System.out.println(year + " " + month + " " + date + " ");
        }
      }
    }
}