code: public static String join(Object[] objects, String separator) {
          String result;
  
          if (objects.length > 0) {
              result = objects[0].toString();
              for (int i = 1; i < objects.length; i++) {
                  result += separator + objects[i].toString();
              }
          } else {
              result = "";
          }
  
          return result;
      }
docs: Joins strings or objects string representations using given separator.
  
  @param objects an array of objects to convert to string and join
  @param separator a string to use a separator
  @return string containing strings joined using separator