用于监视买卖项目列表的说明

Question

我记下来了，你可以在哪里添加你买或卖的东西，有什么建议吗？

  public class Main {

    private static Scanner in = new Scanner(System.in);
    private static String commands = "[-1]Quit, [0]Commands, [1]Available items, [2] Sold items, [3]Add, [4]Delete,"
            + " [5]Edit, [6]Sell. [7]Bilans [8]Details";

    public static void main(String[] args) {

        Storage storage = new Storage(5);

        storage.addItem();


        System.out.println("|   RESELL NOTE    |");
        System.out.println(commands);

        boolean flag = true;
        while (flag) {
            System.out.println("Choose option: (0 - print list)");


            int answer = in.nextInt();
            switch (answer) {

                default:
                    System.out.println("Wrong command");
                    break;

                case -1:
                    System.out.println("QUIT");
                    flag = false;
                    break;

                case 0:
                    System.out.println(commands);
                    break;
                case 1:
                    storage.availableItems();
                    break;
                case 2:
                    storage.soldItems();
                    break;
                case 3:
                    storage.addItem();
                    break;
                case 4:
                    storage.removeItem();
                    break;
                case 5:
                    System.out.println("modify item");
                    break;
                case 6:
                    storage.sellItem();
                    break;
                case 7:
                    storage.bilans();
                    break;
                case 8:
                    storage.details();
            }
        }
    }
}


public class Storage {

    private int maxCapacity;

    public Storage(int maxCapacity) {
        this.maxCapacity = maxCapacity;
    }

    Scanner in = new Scanner(System.in);
    private Map<Integer, Item> items = new TreeMap<>();


    public void availableItems() {
        System.out.println("Available items:");
        for (Map.Entry<Integer, Item> entry : items.entrySet()) {
            if (!entry.getValue().sold) {
                System.out.println(entry.getKey() + ". " + entry.getValue().getName());
            }
        }
    }


    public void soldItems() {
        System.out.println("Sold items:");
        for (Map.Entry<Integer, Item> entry : items.entrySet()) {
            if (entry.getValue().sold) {
                System.out.println(entry.getKey() + "." + entry.getValue().getName()
                        + " - (" + (entry.getValue().soldPrice - entry.getValue().price + "PLN profit)"));
            }
        }
    }

    public void addItem() {
        if (items.size() >= maxCapacity) {
            System.out.println("You cant add more items, storage full! (" + items.size() + "/" + maxCapacity + ")");
        } else {
            items.put(Item.assignId(), new Shoes("Piraty", 1500, 7, "red", 11));
            items.put(Item.assignId(), new Shoes("Belugi", 1500, 7, "red", 11));
            items.put(Item.assignId(), new Shoes("Zebry", 1500, 7, "red", 11));
            items.put(Item.assignId(), new Shoes("Creamy", 1500, 7, "red", 11));
            items.put(Item.assignId(), new Shoes("Sezame", 1500, 7, "red", 11));
            System.out.println("Item added");
        }
    }


    public void modifyItem() { // work in progress
        printInLine();
        System.out.println("\nPick item to modify: ");
        int id = in.nextInt();

        if (items.containsKey(id)) {
            System.out.println("Enter new name for " + items.get(id).getName());
            in.nextLine();
            String newName = in.nextLine();
            items.get(id).setName(newName);
        } else {
            System.out.println("Item not found");
        }
    }

    public void sellItem() {
        printInLine();
        System.out.println("\nChoose item to mark as sold: ");
        int id = in.nextInt();

        if (items.containsKey(id)) {
            items.get(id).setSold(true);
            System.out.println("How much did you get for " + items.get(id).getName() + "?: ");
            items.get(id).setSoldPrice(in.nextInt());
            System.out.println("You marked " + items.get(id).getName() + " as sold");
            System.out.println("Your profit is " + (items.get(id).soldPrice - items.get(id).price) + " PLN");
        } else {
            System.out.println("Item not found");
        }
    }

    public void removeItem() {
        printInLine();
        System.out.println("\nChoose item to remove: ");
        int id = in.nextInt();

        if (items.containsKey(id)) {
            System.out.println(items.get(id).getName() + " removed");
            items.remove(id);
        } else {
            System.out.println("Item not found");
        }
    }


    public void bilans() {

        int spendMoney = 0;
        int earnedMoney = 0;
        int profit = 0;

        for (Map.Entry<Integer, Item> entry : items.entrySet()) {
            if (!entry.getValue().sold) {
                spendMoney += entry.getValue().getPrice();
            } else {
                earnedMoney += entry.getValue().getSoldPrice();
                profit += (entry.getValue().getSoldPrice() - entry.getValue().getPrice());
            }
        }
        System.out.println("You have already spended: " + spendMoney + " PLN");
        System.out.println("You sold items for: " + earnedMoney + " PLN");
        System.out.println("Current profit: " + profit + " PLN");

        if (earnedMoney > spendMoney) {
            System.out.println("Wow, you are on +");
        } else {
            System.out.println("Keep trying");
        }
    }

    public void details() {

        printInLine();
        System.out.print("\nPick item: ");
        int pickItem = in.nextInt();

        if (items.containsKey(pickItem)) {
            System.out.println("\n|  Details |");
            System.out.println("Name: " + items.get(pickItem).getName() +
                    "\nPrice: " + items.get(pickItem).getPrice() +
                    "\nCondition: " + items.get(pickItem).getCondition() + "/10" +
                    "\nColor: ");
        } else {
            System.out.println("Item not found");
        }
    }

    private void printInLine() {
        for (Map.Entry<Integer, Item> entry : items.entrySet()) {
            if (!entry.getValue().isSold()) {
                System.out.print(" - " + entry.getKey() + "." + entry.getValue().getName());
            }
        }
    }
}

Answer 1

boolean flag = true; while (flag) { System.out.println("Choose option: (0 - print list)"); int answer = in.nextInt(); switch (answer) { default: System.out.println("Wrong command"); break; case -1: System.out.println("QUIT"); flag = false; break; case 0: System.out.println(commands); break; case 1: storage.availableItems(); break; case 2: storage.soldItems(); break; case 3: storage.addItem(); break; case 4: storage.removeItem(); break; case 5: System.out.println("modify item"); break; case 6: storage.sellItem(); break; case 7: storage.bilans(); break; case 8: storage.details(); } }

考虑一下

    public static void loop() {
        for (;;) {
            int answer = in.nextInt();
            switch (answer) {
                case -1:
                    System.out.println("QUIT");
                    return;
                case 0:
                    System.out.println(commands);
                    break;
                case 1:
                    storage.availableItems();
                    break;
                case 2:
                    storage.soldItems();
                    break;
                case 3:
                    storage.addItem();
                    break;
                case 4:
                    storage.removeItem();
                    break;
                case 5:
                    System.out.println("modify item");
                    break;
                case 6:
                    storage.sellItem();
                    break;
                case 7:
                    storage.bilans();
                    break;
                case 8:
                    storage.details();
                    break;
                default:
                    System.out.println("Wrong command");
            }
        }
    }

现在我们不需要flag变量了。我们只需永远循环，直到用户输入-1，然后从方法返回。

这使我们可以选择将方法移动到一个单独的类，简化Main类，并允许在多个程序中使用代码。

我发现在结尾使用default大小写比较容易，而且它是唯一没有break的情况。这并不是说另一种形式没有完美的功能。但是，除非您正在使用跌落，否则我只是觉得这样更简单。

考虑在给出无效命令时显示命令列表。因为有时一个人不记得0会打印命令列表。说“打印列表”可能并不意味着它会打印命令列表而不是项目列表。

独立逻辑与显示

你有

public void availableItems() { System.out.println("Available items:"); for (Map.Entry<Integer, Item> entry : items.entrySet()) { if (!entry.getValue().sold) { System.out.println(entry.getKey() + ". " + entry.getValue().getName()); } } }

和

private void printInLine() { for (Map.Entry<Integer, Item> entry : items.entrySet()) { if (!entry.getValue().isSold()) { System.out.print(" - " + entry.getKey() + "." + entry.getValue().getName()); } } }

如果我们换了

    public static void printItemsOnSeparateLines(Iterable<Item> items) {
        for (Item item : items) {
            System.out.println(item.getID() + ". " + item.getName());
        }
    }

    public static void printItemsOnSameLine(Iterable<Item> items) {
        for (Item item : items) {
            System.out.print(" - " + item.getID() + "." + item.getName());
        }
    }

    public List<Item> findAvailableItems() {
        return items.stream.filter(item -> !item.isSold()).collect(Collectors.toList);
    }

    public List<Item> findSoldItems() {
        return items.stream.filter(item -> item.isSold()).collect(Collectors.toList);
    }

现在我们用它们就像

System.out.println("Available items:");
printItemsOnSeparateLines(findAvailableItems());

我们的方法都比较简单。

我还从属性访问更改为isSold。这对我来说读得更好，而且封装得更好。

现在，如果我们想出新的标准，我们可以添加一个新的简单方法，只需重用我们现有的显示方法。或者我们可以添加一个新的显示并重用我们的业务逻辑。

这需要Item包含它的标识符，该标识符可能就在Map键中。

将通用代码重构为新方法

public void sellItem() { printInLine(); System.out.println("\nChoose item to mark as sold: "); int id = in.nextInt(); if (items.containsKey(id)) { items.get(id).setSold(true); System.out.println("How much did you get for " + items.get(id).getName() + "?: "); items.get(id).setSoldPrice(in.nextInt()); System.out.println("You marked " + items.get(id).getName() + " as sold"); System.out.println("Your profit is " + (items.get(id).soldPrice - items.get(id).price) + " PLN"); } else { System.out.println("Item not found"); } }

这可能是

    public void sellItem() {
        printItemsOnSameLine(findAvailableItems());
        Item item = selectItem("\nChoose item to mark as sold: ");
        if (item == null) {
            return;
        }

        if (item.isSold()) {
            System.out.println("That item already sold.");
            return;
        }

        item.setSold(true);
        System.out.println("How much did you get for " + item.getName() + "?: ");
        item.setSoldPrice(in.nextInt());
        System.out.println("You marked " + item.getName() + " as sold");
        System.out.println("Your profit is " + (item.soldPrice - item.price) + " PLN");
    }

使用

    public Item selectItem(String query) {
        System.out.println(query);

        Item item = items.get(in.nextInt();
        if (item == null) {
            System.out.println("Item not found.");
        }

        return item;
    }

现在，我们不必不断地重写相同的代码(四次)。如果我们想要选择一个项目，我们可以调用该方法。

我还处理了一个原始代码没有的条件。如果有人输入了已经售出的物品的ID怎么办？

这段代码不是重复编写items.get(id)，而是使用item。

我们不需要调用containsKey，因为我们只需调用get就可以得到相同的行为，无论如何我们都必须调用它。现在我们不用随身携带身份证了。

逻辑错误？

for (Map.Entry<Integer, Item> entry : items.entrySet()) { if (!entry.getValue().sold) { spendMoney += entry.getValue().getPrice(); } else { earnedMoney += entry.getValue().getSoldPrice(); profit += (entry.getValue().getSoldPrice() - entry.getValue().getPrice()); } }

稍后，您将比较spendMoney和earnedMoney。但两者是不可比拟的。他们在不同的项目上。考虑一下

        for (Item item : values()) {
            spentMoney += item.getPrice();
            if (item.isSold()) {
                earnedMoney += item.getSoldPrice();
                profit += item.getSoldPrice() - item.getPrice();
            }
        }

现在，我们有了购买所有物品所花费的金额，而不是目前售出的物品所赚的钱。我们知道我们现在是否领先。或者，我们可以看看利润，看看我们在已经售出的产品上是否领先。

我也从entrySet更改为values，因为您从未使用过密钥。所以我们可以说是item而不是entry.getValue()。

我将spendMoney改为spentMoney，以与earnedMoney保持一致。