code: public static boolean delimitedStringContains(
              String delimitedString, char delimiter, String item) {
          if (isEmpty(delimitedString) || isEmpty(item)) {
              return false;
          }
          int pos = -1;
          int length = delimitedString.length();
          while ((pos = delimitedString.indexOf(item, pos + 1)) != -1) {
              if (pos > 0 && delimitedString.charAt(pos - 1) != delimiter) {
                  continue;
              }
              int expectedDelimiterPos = pos + item.length();
              if (expectedDelimiterPos == length) {
                  // Match at end of string.
                  return true;
              }
              if (delimitedString.charAt(expectedDelimiterPos) == delimiter) {
                  return true;
              }
          }
          return false;
      }
docs: Does a comma-delimited list 'delimitedString' contain a certain item?
  (without allocating memory)
  
  @hide