code: private void checkTileOverFlow() throws MahjongTileOverFlowException {
          //
          for (int i = 0; i < handsComp.length; i++) {
              int hand = handsComp[i];
              if (hand > 4) {
                  canWin = false;
                  throw new MahjongTileOverFlowException(i, hand);
              }
          }
      }
docs: 同じ牌が5個以上はありえないので、Exception をthrow
  
  @throws MahjongTileOverFlowException