本文為英文版的機器翻譯版本，如內容有任何歧義或不一致之處，概以英文版為準。

# （選用） 擴展消費者
<a name="tutorial-stock-data-kplkcl2-consumer-extension"></a>

此一選用章節示範如何就更為複雜的情境擴充消費者程式碼。

如果您想知道每分鐘銷售量最高的訂單，則可修改三處位置的 `StockStats` 類別以納入這項新的優先等級。

**擴充消費者**

1. 加入新的執行個體變數：

   ```
    // Ticker symbol of the stock that had the largest quantity of shares sold 
    private String largestSellOrderStock;
    // Quantity of shares for the largest sell order trade
    private long largestSellOrderQuantity;
   ```

1. 為 `addStockTrade` 添加以下程式碼：

   ```
   if (type == TradeType.SELL) {
        if (largestSellOrderStock == null || trade.getQuantity() > largestSellOrderQuantity) {
            largestSellOrderStock = trade.getTickerSymbol();
            largestSellOrderQuantity = trade.getQuantity();
        }
    }
   ```

1. 修改 `toString` 方法以列印其他資訊：

   ```
    
   public String toString() {
       return String.format(
           "Most popular stock being bought: %s, %d buys.%n" +
           "Most popular stock being sold: %s, %d sells.%n" +
           "Largest sell order: %d shares of %s.",
           getMostPopularStock(TradeType.BUY), getMostPopularStockCount(TradeType.BUY),
           getMostPopularStock(TradeType.SELL), getMostPopularStockCount(TradeType.SELL),
           largestSellOrderQuantity, largestSellOrderStock);
   }
   ```

若您現在執行消費者 (記得也要執行生產者)，應會看到類似以下內容的輸出：

```
 
  ****** Shard shardId-000000000001 stats for last 1 minute ******
  Most popular stock being bought: WMT, 27 buys.
  Most popular stock being sold: PTR, 14 sells.
  Largest sell order: 996 shares of BUD.
  ****************************************************************
```

## 後續步驟
<a name="tutorial-stock-data-kplkcl2-consumer-extension-next"></a>

[清除資源](tutorial-stock-data-kplkcl2-finish.md)