如何在"Sales Report File"中展示所有已订购商品？附现有代码

First, let's fix an immediate bug in your switch statement—you’re missing a break after the "Cookies" case, which would cause the code to fall through to the "Sales Report File" case every time someone buys cookies. Then, we’ll add a way to track the quantity of each product sold, and use that to build your sales report correctly.

Step 1: Add a Sales Tracking Map #

We’ll use a HashMap to keep count of how many times each product has been ordered. Add this as a class-level variable:

private final Map<String, Integer> salesCount = new HashMap<>();

Step 2: Update Sales Count When Selling Products #

Modify each product case in your actionPerformed method to update the map only when a sale is successful. For example, for Candy:

case "Candy":
    if (sellProduct(candy, "Candy")) { // Assuming sellProduct returns true if the sale worked
        salesCount.put("Candy", salesCount.getOrDefault("Candy", 0) + 1);
    }
    break;

(Note: I added a check for successful sales—adjust this based on whether your sellProduct method returns a boolean. If it doesn’t, you can skip the check, but it’s better to only count valid sales.)

Step 3: Generate the Sales Report String #

When the "Sales Report File" button is clicked, build a dynamic string that lists each product and its quantity:

case "Sales Report File":
    StringBuilder report = new StringBuilder("Items Sold:\n");
    for (Map.Entry<String, Integer> entry : salesCount.entrySet()) {
        report.append(entry.getKey()).append(": ").append(entry.getValue()).append("\n");
    }
    // Add a message if no items were sold
    if (salesCount.isEmpty()) {
        report.append("No items have been sold yet.");
    }
    JOptionPane.showMessageDialog(null, report.toString(), "Sales Report ~ ", JOptionPane.PLAIN_MESSAGE);
    break;

Full Modified Code #

Here’s the updated version of your class with all these changes:

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.HashMap;
import java.util.Map;
import javax.swing.JButton;
import javax.swing.JOptionPane;

// Assume Dispenser class is defined elsewhere
class Dispenser {
    private int count;
    private int price;
    public Dispenser(int count, int price) {
        this.count = count;
        this.price = price;
    }
    // Example sell method—adjust to match your actual implementation
    public boolean sell() {
        if (count > 0) {
            count--;
            return true;
        }
        return false;
    }
}

public class VendingMachine {
    private final Dispenser candy = new Dispenser(100, 50);
    private final Dispenser chips = new Dispenser(100, 65);
    private final Dispenser gum = new Dispenser(75, 45);
    private final Dispenser cookies = new Dispenser(100, 85);
    private final JButton candyB;
    private final JButton chipsB;
    private final JButton gumB;
    private final JButton cookiesB;
    private final Map<String, Integer> salesCount = new HashMap<>();

    // Constructor to initialize buttons
    public VendingMachine() {
        candyB = new JButton("Candy");
        chipsB = new JButton("Chips");
        gumB = new JButton("Gum");
        cookiesB = new JButton("Cookies");
        
        // Attach listeners to buttons
        candyB.addActionListener(new ButtonHandler());
        chipsB.addActionListener(new ButtonHandler());
        gumB.addActionListener(new ButtonHandler());
        cookiesB.addActionListener(new ButtonHandler());
    }

    // Updated sellProduct method to return success status
    private boolean sellProduct(Dispenser dispenser, String productName) {
        boolean success = dispenser.sell();
        if (success) {
            JOptionPane.showMessageDialog(null, "Sold " + productName, "Success", JOptionPane.INFORMATION_MESSAGE);
        } else {
            JOptionPane.showMessageDialog(null, productName + " is out of stock!", "Error", JOptionPane.ERROR_MESSAGE);
        }
        return success;
    }

    private class ButtonHandler implements ActionListener {
        public void actionPerformed(ActionEvent e) {
            switch (e.getActionCommand()) {
                case "Exit":
                    System.exit(0);
                    break;
                case "Candy":
                    if (sellProduct(candy, "Candy")) {
                        salesCount.put("Candy", salesCount.getOrDefault("Candy", 0) + 1);
                    }
                    break;
                case "Chips":
                    if (sellProduct(chips, "Chips")) {
                        salesCount.put("Chips", salesCount.getOrDefault("Chips", 0) + 1);
                    }
                    break;
                case "Gum":
                    if (sellProduct(gum, "Gum")) {
                        salesCount.put("Gum", salesCount.getOrDefault("Gum", 0) + 1);
                    }
                    break;
                case "Cookies":
                    if (sellProduct(cookies, "Cookies")) {
                        salesCount.put("Cookies", salesCount.getOrDefault("Cookies", 0) + 1);
                    }
                    break; // Fixed missing break!
                case "Sales Report File":
                    StringBuilder report = new StringBuilder("Items Sold:\n");
                    for (Map.Entry<String, Integer> entry : salesCount.entrySet()) {
                        report.append(entry.getKey()).append(": ").append(entry.getValue()).append("\n");
                    }
                    if (salesCount.isEmpty()) {
                        report.append("No items have been sold yet.");
                    }
                    JOptionPane.showMessageDialog(null, report.toString(), "Sales Report ~ ", JOptionPane.PLAIN_MESSAGE);
                    break;
                default:
                    break;
            }
        }
    }
}

Key Notes: #

• Sales Tracking: The HashMap keeps track of how many times each product was successfully sold—so if someone buys 2 cookies, it will show "Cookies: 2" in the report.
• Fixed Fallthrough: Added the missing break in the "Cookies" case to prevent accidental triggering of the sales report.
• Dynamic Report: The report builds itself based on actual sales data, so it will only show products that have been ordered.
• Success Check: We only increment the sales count if the product was available and sold successfully.

内容的提问来源于stack exchange，提问作者Xen