code: public static String prettyUptimeStr(int secs) {
          int diversize = PRETTYSECDIVIDERS.length;
  
          List<String> tmp = new ArrayList<String>();
          int div = secs;
          for (int i = 0; i < diversize; i++) {
              if (PRETTYSECDIVIDERS[i][1] != null) {
                  Integer d = Integer.parseInt(PRETTYSECDIVIDERS[i][1]);
                  tmp.add(div % d + PRETTYSECDIVIDERS[i][0]);
                  div = div / d;
              } else {
                  tmp.add(div + PRETTYSECDIVIDERS[i][0]);
              }
          }
  
          String rtn = "";
          int tmpSzie = tmp.size();
          for (int j = tmpSzie - 1; j > -1; j--) {
              rtn += tmp.get(j);
          }
          return rtn;
      }
docs: seconds to string like 1d20h30m40s
  
  @param secs
  @return