Question

我一直在编写一个银行业务计划，但是我在撤销后改变现有余额时遇到了问题。它第一次工作，但第二次回到原始数量。如果我有300美元，然后提取50美元，它将显示250美元。然而，在它第二次执行并且我提取20美元之后，它将显示我的余额是280美元而不是230美元我的程序需要有两种方法加上main方法，我目前的帐户余额为300美元。它还需要一个主菜单。

我的老师说我们不能使用数组，因为我们还没有讨论它。这是我第一次使用的不仅仅是main方法，因此我选择的方法可能是错误的。

import java.util.Scanner;

public class BankingATM {
    public static void main(String[] args) {
        double withdraw = withdrawAmount();
        double myBalance = withdrawAmount();
        balanceAmount(withdraw, myBalance);
    }

    public static double withdrawAmount() {
        Scanner keyboard = new Scanner(System.in);
        int option;
        double myBalance;
        double withdraw = 0;
        myBalance = 300 - withdraw;

        do {
            System.out.println("Please select an option:");
            System.out.println("Press 1 the withdraw from you account.");
            System.out.println("Press 2 to check your balance");
            System.out.println("Press 3 to Exit");
            {
                option = keyboard.nextInt();
                if (option == 1) {
                    System.out.println("User selected to withdraw");
                    System.out.println("How much would you like to withdraw?");
                    withdraw = keyboard.nextDouble();
                    myBalance = 300;
                    double newBalance = myBalance - withdraw;
                    {
                        if (withdraw > 500) {
                            System.out.println("Sorry but the ATM has a limit of $500.00");
                        } else if (withdraw > myBalance && withdraw > 500) {
                            System.out.println("Sorry your account only has $300.00");
                        } else if (withdraw > myBalance) {
                            System.out.println("Sorry your account only has $300.00");
                        } else if (withdraw <= myBalance) {
                            System.out.println("The machine is realeasing $" + withdraw);
                            System.out.println("Your current balance is $" + (myBalance - withdraw));
                        }
                    }
                }
                if (option == 2) {
                    System.out.println("User selected to check balance");
                    balanceAmount(withdraw, myBalance);
                }
                if (option == 3) {
                    System.out.println("User chose to exit");
                    System.exit(0);
                }
            }
        } while (option != 1 || option != 2 || option != 3);
        return myBalance;
    }

    public static void balanceAmount(double withdraw, double myBalance) {
        System.out.println("Your balance is" + myBalance);
    }
}

Answer 1

好吧，无论何时取款，你都要将余额初始化为300：

    if(option == 1)
    {
        System.out.println("User selected to withdraw");
        System.out.println("How much would you like to withdraw?");
        withdraw = keyboard.nextDouble();
        myBalance = 300; // you should remove that line.

此外，如果您打算多次调用withdrawAmount()，则不应将myBalance变量声明为该方法中的局部变量，因为每次调用该方法都会重置余额。

Answer 2

删除此行：

 myBalance = 300; // you should remove that line.

Answer 3

在do .. while循环中，进行以下更改： // myBalance = 300; //删除此行 double myBalance = myBalance - 撤回; //分配新值myBalance

银行账户的方法

3 个答案: