自动售货机上的 StackOverflow 错误答案

【问题标题】：StackOverflow Error on vending machine自动售货机上的 StackOverflow 错误
【发布时间】：2014-06-17 07:05:20
【问题描述】：

我为我的期末课程编写了一个自动售货机程序，但我不断收到堆栈溢出错误。我相信它与继承有关，但不确定，我试过在没有帮助的情况下改变它。

非常感谢你们的任何帮助。谢谢。

这是我的程序：

package vendingmachine;

import java.text.NumberFormat;
import javax.swing.JOptionPane;

public class VendingMachine {
    public static void main(String[] args) {
        VendMachine freestyle = new VendMachine();
        int selectedOption = JOptionPane.showConfirmDialog(null, "Would you like to use the vending        machine?", "Vending Machine",
                JOptionPane.YES_NO_OPTION);
        if (selectedOption == JOptionPane.NO_OPTION) {
            System.exit(selectedOption);
        } else {
            freestyle.offerChoice();
        }
    }
}

class VendMachine {
    Snacks temp = new Snacks();
    private float moneyPaid = 0;
    int maxBevCount = 50;
    int maxSnackCount = 100;
    float itemPrice = .65f;
    private final String coke = "Coke Zero";
    private final String sprite = "Sprite Zero";
    private final String water = "Dasani";
    private float moneyReturned = 0;
    private int ask;
    NumberFormat formating = NumberFormat.getCurrencyInstance();

    public void offerChoice() {
        ask = Integer.parseInt(JOptionPane.showInputDialog(null, "Would you like a Snack: 1 or  Beverage: 2 ", "Vending Machine",
                JOptionPane.INFORMATION_MESSAGE));
        if (ask == 1) {
            temp.askUser();
        } else {
            int askBevType = Integer.parseInt(JOptionPane.showInputDialog(null, "What type of beverage would you like? " + coke + ": 1 " + sprite
                    + ": 2 " + water + ": 3 " + "Quit: 4 ", "Vending Machine", JOptionPane.INFORMATION_MESSAGE));
            switch (askBevType) {
            case 1: {
                JOptionPane.showMessageDialog(null, "you chose " + coke + " the price is: " + formating.format(itemPrice));
                addMoney();
                break;
            }
            case 2: {
                JOptionPane.showMessageDialog(null, "you chose " + sprite + " the price is: " + formating.format(itemPrice));
                addMoney();
                break;
            }
            case 3: {
                JOptionPane.showMessageDialog(null, "you chose " + water + " the price is: " + formating.format(itemPrice));
                addMoney();
                break;
            }
            case 4: {
                System.exit(0);
            }
            default: {
                break;
            }
            }
        }
    }

    public float addMoney() {
        moneyPaid = Float.parseFloat(JOptionPane.showInputDialog(null, " insert your money", "Vending Machine", JOptionPane.INFORMATION_MESSAGE));
        while (true) {
            if (moneyPaid == itemPrice) {
                vend();
            }
            if (moneyPaid < itemPrice) {
                JOptionPane.showMessageDialog(null, "that's not enough... please insert more money!", "Vending Machine", JOptionPane.ERROR_MESSAGE);
                float moreCashIn = Float.parseFloat(JOptionPane.showInputDialog(null, "The items cost " + formating.format(itemPrice)
                        + " insert your money.", "Vending Machine", JOptionPane.INFORMATION_MESSAGE));
                if (moreCashIn >= itemPrice) {
                    vend();
                }
            } else if (moneyPaid > itemPrice) {
                moneyReturned = moneyPaid - itemPrice;
                vend();
                JOptionPane.showMessageDialog(null, "And here is your change of " + formating.format(moneyReturned), "Vending Machine",
                        JOptionPane.INFORMATION_MESSAGE);
            }
            return moneyPaid;
        }
    }

    public void vend() {
        JOptionPane.showMessageDialog(null, "Vending........Here you go. Have a nice day!", "Vending Machine", JOptionPane.INFORMATION_MESSAGE);
        restock();
    }

    public void restock() {
        if (ask == 2) {
            maxBevCount -= 1;
            JOptionPane.showMessageDialog(null, "Beverage Stock in the machine is now " + maxBevCount, "Vending Machine",
                    JOptionPane.INFORMATION_MESSAGE);
            maxBevCount += 1;
            JOptionPane.showMessageDialog(null, "Machine is now restocked with " + maxBevCount + " Beverages ", "Vending Machine",
                    JOptionPane.INFORMATION_MESSAGE);
        } else {
            maxSnackCount -= 1;
            JOptionPane.showMessageDialog(null, "Stock in the machine is now " + maxSnackCount, "Vending Machine", JOptionPane.INFORMATION_MESSAGE);
            maxSnackCount += 1;
            JOptionPane.showMessageDialog(null, "Machine is now restocked with " + maxSnackCount + " items", "Vending Machine",
                    JOptionPane.INFORMATION_MESSAGE);
        }
    }
}

class Snacks extends VendMachine {
    int askSnackType;
    EmAndM emAndM = new EmAndM("M&M's", 180, 1.80f);
    Snickers snickers = new Snickers("Snickers", 280, 2.50f);
    Gum gum = new Gum("Gum", 110, 1.25f);
    Popcorn popcorn = new Popcorn("Popcorn", 190, 2.30f);
    Crackers crackers = new Crackers("Crackers", 130, 1.90f);
    Chips chips = new Chips("Chips", 140, 1.70f);

    public void askUser() {
        askSnackType = Integer.parseInt(JOptionPane.showInputDialog(null, "Would you like some- " + emAndM.name + ": 1 " + snickers.name + ": 2 "
                + gum.name + ": 3 " + popcorn.name + ": 4 " + crackers.name + ": 5 " + chips.name + ": 6 " + " Quit: 7 ", "Vending Machine",
                JOptionPane.INFORMATION_MESSAGE));
        switch (askSnackType) {
        case 1: {
            JOptionPane.showMessageDialog(null,
                    "You chose " + emAndM.name + " , Calories: " + emAndM.calories + " the price is: " + formating.format(emAndM.price));
            addMoney();
            break;
        }
        case 2: {
            JOptionPane.showMessageDialog(null,
                    "You chose " + snickers.name + " , Calories: " + snickers.calories + " the price is: " + formating.format(snickers.price));
            addMoney();
            break;
        }
        case 3: {
            JOptionPane.showMessageDialog(null,
                    "You chose " + gum.name + " , Calories: " + gum.calories + " the price is: " + formating.format(gum.price));
            addMoney();
            break;
        }
        case 4: {
            JOptionPane.showMessageDialog(null,
                    "You chose " + popcorn.name + " , Calories: " + popcorn.calories + " the price is: " + formating.format(popcorn.price));
            addMoney();
            break;
        }
        case 5: {
            JOptionPane.showMessageDialog(null,
                    "You chose " + crackers.name + " , Calories: " + crackers.calories + " the price is: " + formating.format(crackers.price));
            addMoney();
            break;
        }
        case 6: {
            JOptionPane.showMessageDialog(null,
                    "You chose " + chips.name + " , Calories: " + chips.calories + " the price is: " + formating.format(chips.price));
            addMoney();
            break;
        }
        case 7: {
            System.exit(0);
        }
        default: {
            break;
        }
        }
    }

    class SugarySnacks {}

    class EmAndM extends Snacks {
        String name;
        int calories;
        float price;

        EmAndM(String brand, int cal, float cost) {
            name = brand;
            calories = cal;
            price = cost;
        }
    }

    class Snickers extends Snacks {
        String name;
        int calories;
        float price;

        Snickers(String brand, int cal, float cost) {
            name = brand;
            calories = cal;
            price = cost;
        }
    }

    class Gum extends Snacks {
        String name;
        int calories;
        float price;

        Gum(String brand, int cal, float cost) {
            name = brand;
            calories = cal;
            price = cost;
        }
    }

    class SaltySnacks {}

    class Popcorn extends Snacks {
        String name;
        int calories;
        float price;

        Popcorn(String brand, int cal, float cost) {
            name = brand;
            calories = cal;
            price = cost;
        }
    }

    class Crackers extends Snacks {
        String name;
        int calories;
        float price;

        Crackers(String brand, int cal, float cost) {
            name = brand;
            calories = cal;
            price = cost;
        }
    }

    class Chips extends Snacks {
        String name;
        int calories;
        float price;

        Chips(String brand, int cal, float cost) {
            name = brand;
            calories = cal;
            price = cost;
        }
    }
}

【问题讨论】：

Stacktrace 将列出导致溢出的方法。
您需要更好地格式化您发布的代码。我不是在为你调试你的程序，但我会给你一个提示。 “堆栈”是已调用的一系列方法。每次调用一个方法时，它都会被添加到堆栈的顶部，当它完成时，它会被移除。如果方法 A 调用另一个方法 B，则 B 将被放置在堆栈中 A 的顶部。如果 B 调用了另一个方法 C，那么它将被放置在 B 的顶部。当堆栈上的调用过多时，会发生溢出。所以看看你是否能知道方法在哪里被调用（添加）但永远不会结束（删除）。
我强烈建议使用一致的缩进来使代码更易于阅读。
class SugarySnacks {} 喜欢这个
Gum 扩展了 Snacks，Snacks 扩展了 VendMachine。 Snack 是一种自动售货机（但不是 VendingMachine；它是与 VendMachine 不同的类）。

标签： java

【解决方案1】：

解决了我的问题，在我的 VendMachine 类中，我在 Snack 类中创建了临时对象。这导致堆栈溢出。我通过在 offerChoice 方法中创建相同的临时对象解决了这个问题。

这里是修改区域：

类 VendMachine {

Snacks temp = new Snacks();**//removed this object**
private float moneyPaid = 0;
int maxBevCount = 50;
int maxSnackCount = 100;
float itemPrice = .65f;
private final String coke = "Coke Zero";
private final String sprite = "Sprite Zero";
private final String water = "Dasani";
private float moneyReturned = 0;
private int ask;
NumberFormat formating = NumberFormat.getCurrencyInstance();

public void offerChoice(){
    Snacks temp = new Snacks(); **//Inserted same object under this method**
    ask = Integer.parseInt(JOptionPane.showInputDialog(null, "Would you like a Snack: 1 or Beverage: 2 ", "Vending Machine", JOptionPane.INFORMATION_MESSAGE));
    if (ask == 1){

        temp.askSnackType();

【讨论】：