code: @Override
      public boolean matches(int lineNumber, String line) {
          if (lineNumber == 4
              && line.length() > 7
              && (!line.contains("2000")) && // MDL Mol V2000 format
              (!line.contains("3000"))) // MDL Mol V3000 format
          {
              // possibly a MDL mol file
              try {
                  String atomCountString = line.substring(0, 3).trim();
                  String bondCountString = line.substring(3, 6).trim();
                  Integer.valueOf(atomCountString);
                  Integer.valueOf(bondCountString);
                  String remainder = line.substring(6).trim();
                  for (int i = 0; i < remainder.length(); ++i) {
                      char c = remainder.charAt(i);
                      if (!(Character.isDigit(c) || Character.isWhitespace(c))) {
                          return false;
                      }
                  }
              } catch (NumberFormatException nfe) {
                  // Integers not found on fourth line; therefore not a MDL file
                  return false;
              }
              return true;
          }
          return false;
      }
docs: {@inheritDoc}