Review

class PassportService {
   /**
    * Reads the type of document.
    * The ICAO documentation gives "P<" as an example.
    * 
    * @return a string of length 2 containing the document type
    * @throws IOException if something goes wrong
    */
   public String readDocumentType() throws IOException {
      byte[] fileData = readMRZ();
      DataInputStream in = new DataInputStream(new ByteArrayInputStream(fileData));
      byte[] result = new byte[2];
      in.readFully(result);
      return new String(result);
   }

}