code: private void checkTokenized() {
          if (tokens == null) {
              if (chars == null) {
                  // still call tokenize as subclass may do some work
                  final List<String> split = tokenize(null, 0, 0);
                  tokens = split.toArray(new String[split.size()]);
              } else {
                  final List<String> split = tokenize(chars, 0, chars.length);
                  tokens = split.toArray(new String[split.size()]);
              }
          }
      }
docs: Checks if tokenization has been done, and if not then do it.