java Map<String，Deque<Block>>需要值帮助

Question

我是初学者，所以请对我放松点。我必须创建一个存储不同3个字母的股票代码、股票价格和购买价格的股票程序。然后召回它们，以不同的价格出售。我的问题是，我似乎无法在地图上适当地增加更多的股票价值。当我在其中放入一个不同的值时，它会擦除第一个值，或者至少看起来是这样。My Block类（未列出）将最新的键和值返回到下面列出的代码。我的代码和结果如下所示：

    private String getPurchaseMap(String stockCode, Double quantityPurchased, Double purchasePrice) {
            var stock = new Block(stockCode, quantityPurchased, purchasePrice);
            var deque = new ArrayDeque<Block>();


           if (!maintainStocks.containsKey(stockCode)) {
               deque = new ArrayDeque<Block>();
               deque.offerFirst(stock);
               maintainStocks.put(stockCode, deque);
           } else {

               deque.offer(stock);
               maintainStocks.put(stockCode, deque);
           }

                var tempObj = maintainStocks.get(stockCode).peekFirst();
                for (var stocks : maintainStocks.entrySet()) {
                    System.out.printf("%s%n", stocks.getKey());

                    for (var test : stocks.getValue()) {
                        System.out.println(tempObj.getQuantity());
                        System.out.println(tempObj.getPrice());
                    }
                }

                return null;
        }

    The results are:
    -Would you like to (B)uy, (S)ell stock or (E)xit? > b
    -Please enter the 3-letter stock code > aaa
    -Please enter the quantity to purchase > 10
    -Please enter the price per share > 15
    -aaa
    -10.0
    -15.0
    -Would you like to pursue another transaction? (Y)es or (N)o > y
    -Would you like to (B)uy, (S)ell stock or (E)xit? > b
    -Please enter the 3-letter stock code > aaa
    -Please enter the quantity to purchase > 11
    -Please enter the price per share > 16
    -aaa
    -11.0
    -16.0
    -Would you like to pursue another transaction? (Y)es or (N)o > n
    -Thank you for your consideration. Solution exiting.