java - 披萨价格没有更新

Question

我决定完全放弃我的上一个项目并重做它。这次我的问题是我无法正确计算价格。你介意看看我的代码并告诉我我需要做什么来修复它吗？

先感谢您！

import java.awt.*;

import javax.swing.*;
import java.text.DecimalFormat;
import java.awt.event.*;
import java.text.DecimalFormat;

class JFrameWithComponents extends JFrame implements ItemListener {

    DecimalFormat fmt = new DecimalFormat("0.00");
    final int BASE_PRICE = 7;
    int totalPrice = BASE_PRICE;
    int toppings = 0;
    String output;

    JLabel title = new JLabel("Steve's Pizzeria");
    Font headlineFont = new Font("Courier", Font.BOLD, 40);
    JLabel info = new JLabel("What would you like on your pizza?");
    Font infoFont = new Font("Courier", Font.BOLD, 18);
    JLabel info2 = new JLabel("What size of pizza do you wish to order?");
    Font info2Font = new Font("Courier", Font.BOLD, 18);
    JLabel info3 = new JLabel("Your total is: ");
    Font info3Font = new Font("Courier", Font.BOLD, 24);

    JCheckBox extraCheeseBox = new JCheckBox("Extra Cheese", false);
    JCheckBox pepperoniBox = new JCheckBox("Pepperoni", false);
    JCheckBox sausageBox = new JCheckBox("Sausage", false);
    JCheckBox groundBeefBox = new JCheckBox("Ground Beef", false);
    JCheckBox onionBox = new JCheckBox("Onions", false);
    JCheckBox mushroomBox = new JCheckBox("Mushrooms", false);
    JCheckBox blackOlivesBox = new JCheckBox("Black Olives", false);
    JCheckBox greenPeppersBox = new JCheckBox("Green Peppers", false);
    JCheckBox jalepenosBox = new JCheckBox("Jalepenos", false);

    JTextField totPrice = new JTextField(10);
    JComboBox pizzaBox = new JComboBox();

    final int WIDTH = 650;
    final int HEIGHT = 250;

    int[] pizzaPrice = { 7, 9, 11, 14 };

    public JFrameWithComponents() {
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setLayout(new FlowLayout());
        setSize(WIDTH, HEIGHT);
        add(title);
        title.setFont(headlineFont);

        add(info2);
        info2.setFont(info2Font);
        add(pizzaBox);
        add(info);

        add(extraCheeseBox);
        add(pepperoniBox);
        add(sausageBox);
        add(groundBeefBox);
        add(onionBox);
        add(mushroomBox);
        add(blackOlivesBox);
        add(greenPeppersBox);
        add(jalepenosBox);
        add(info3);
        info3.setFont(info3Font);
        add(totPrice);

        pizzaBox.addItem("small ($7)");
        pizzaBox.addItem("medium ($9)");
        pizzaBox.addItem("large ($11)");
        pizzaBox.addItem("extra large ($14)");

        pizzaBox.addItemListener(this);

        extraCheeseBox.addItemListener(this);
        pepperoniBox.addItemListener(this);
        sausageBox.addItemListener(this);
        groundBeefBox.addItemListener(this);
        onionBox.addItemListener(this);
        mushroomBox.addItemListener(this);
        blackOlivesBox.addItemListener(this);
        greenPeppersBox.addItemListener(this);
        jalepenosBox.addItemListener(this);
    }

    public void itemStateChanged(ItemEvent event) {
        Object source = event.getSource();
        int select = event.getStateChange();

        if (source == extraCheeseBox) {
            if (select == ItemEvent.SELECTED) {
                toppings += 1;
            } else
                toppings -= 1;
        } else if (source == pepperoniBox) {
            if (select == ItemEvent.SELECTED)
                toppings += 1.00;
            else
                toppings -= 1.00;
        } else if (source == sausageBox) {
            if (select == ItemEvent.SELECTED)
                toppings += 1.00;
            else
                toppings -= 1.00;
        } else if (source == groundBeefBox) {
            if (select == ItemEvent.SELECTED)
                toppings += 1.00;
            else
                toppings -= 1.00;
        } else if (source == onionBox) {
            if (select == ItemEvent.SELECTED)
                toppings += 1.00;
            else
                toppings -= 1.00;
        } else if (source == mushroomBox) {
            if (select == ItemEvent.SELECTED)
                toppings += 1.00;
            else
                toppings -= 1.00;
        } else if (source == blackOlivesBox) {
            if (select == ItemEvent.SELECTED)
                toppings += 1.00;
            else
                toppings -= 1.00;
        } else if (source == greenPeppersBox) {
            if (select == ItemEvent.SELECTED)
                toppings += 1.00;
            else
                toppings -= 1.00;
        } else if (select == ItemEvent.SELECTED)
            toppings += 1.00;
        else
            toppings -= 1.00;
        totPrice.setText("$ " + fmt.format(toppings) + pizzaPrice);

        output = "$ " + (totalPrice + toppings);
        totPrice.setText(output);
    }

}

public class JPizza {

    public static void main(String[] args) {
        JFrameWithComponents frame = new JFrameWithComponents();
        frame.setVisible(true);
    }
}
// end of class

Answer 1

根据您的代码，您应该简单地从头开始重新计算价格，不要加减值，因为状态很容易出错。

此外，您不包括比萨饼的价格。

更好的解决方案是将总数的计算与事件完全分开......

例如...

@Override
public void itemStateChanged(ItemEvent event) {

    double total = getTotal();
    totPrice.setText(NumberFormat.getCurrencyInstance().format(total));
}

protected double getTotal() {
    double total = 0;
    total = pizzaPrice[pizzaBox.getSelectedIndex()];

    total += extraCheeseBox.isSelected() ? 1 : 0;
    total += pepperoniBox.isSelected() ? 1 : 0;
    total += sausageBox.isSelected() ? 1 : 0;
    total += groundBeefBox.isSelected() ? 1 : 0;
    total += onionBox.isSelected() ? 1 : 0;
    total += mushroomBox.isSelected() ? 1 : 0;
    total += blackOlivesBox.isSelected() ? 1 : 0;
    total += greenPeppersBox.isSelected() ? 1 : 0;
    total += jalepenosBox.isSelected() ? 1 : 0;
    return total;
}