code: public int findFirst(String str, String search) {
          return (str == null || search == null) ? -1 :
              str.indexOf(search);
      }
docs: Finds the index of the first occurrence of the given search string in
  the source string, or -1 if not found.
  
  @param str the source string
  @param search the string to search for
  
  @return the start index of the found string or -1 if not found