code: private boolean isNumber(String in1) {
          //noinspection LoopStatementThatDoesntLoop
          for (StringTokenizer stringTokenizer = new StringTokenizer(in1, numberCharacters); stringTokenizer.hasMoreTokens(); ) {
              return false;
          }
          return true;
      }
docs: Checks whether input string contains a number or not.
  
  @param in1 input string
  @return false if it contains a number