code: private boolean checkAnswer(String input) {
          StringTokenizer tok = new StringTokenizer(validAnswers, ANSWER_SEPARATOR);
  
          while (tok.hasMoreTokens()) {
              if (tok.nextElement().toString().trim().equalsIgnoreCase(input.trim())) {
                  return true;
              }
          }
  
          log.info("User input is not valid - must be one of " + validAnswers);
  
          return false;
      }
docs: Validate given input according to valid answer tokens.
  @param input
  @return