Question

我用Java做作业。我的任务是建立一家可以提取，存款和查询余额的银行。我的问题是充值和提款后我无法更新余额...我已经尽了一切努力，但仍然无法理解逻辑。有人可以帮忙添加到我的程序中吗...谢谢

import java.util.Scanner;

public class bankJava 
{

    Scanner input = new Scanner(System.in);


    double balance;
    double amount;

    public void withdraw() 
    {

        System.out.println("Enter amount: ");
        amount = input.nextInt();

        balance = balance - amount;


    }

    public void deposit()
    {

        System.out.println("Enter amount: ");
        amount = input.nextInt();
        balance = balance + amount;

    }

    public void accBalance()
    {


    }



}

--------------------------------- MAIN ------------- -------------------

import java.util.Scanner;

public class bankJavaTest {

    public static void main(String[] args){

        Scanner input = new Scanner(System.in);

        int action;

        bankJava wdraw = new bankJava();
        bankJava dposit = new bankJava();
        bankJava balanceInquiry = new bankJava();
        bankJava amount = new bankJava();

        do{

        System.out.println("Choose Action: ");
        System.out.println("(1) Withdraw");
        System.out.println("(2) Deposit");
        System.out.println("(3) Balance Inquiry");
        System.out.println("(4) Exit");
        action = input.nextInt();


        switch(action){



        //---------WITHDRAW------------//
        case 1 :

            System.out.println("******Withdraw******");
            wdraw.withdraw();
            System.out.println("***************************");


            break;

        //---------DEPOSIT------------//
        case 2 :

            System.out.println("******Deposit******");
            dposit.deposit();
            System.out.println("***************************");
            break;

        //-----------Balance Inquiry-------//
        case 3 :

            System.out.println("******Balance Inquiry******");
            balanceInquiry.accBalance();
            System.out.println("***************************");

            break;

        case 4 :

            System.out.println("Thank you for choosing our bank!");
            break;

        default :

            System.out.println("Invalid action.");
            break;

        } 
        }while(action != 4);

    }


}

Answer 1

为什么要对4个不同的JavaBank进行注册？对每个操作执行此操作，您将在不同的对象中执行每个方法。如果我很了解您的问题，我认为您可以轻松地在同一对象中解决问题。

import java.util.Scanner;

public class bankJavaTest {

    public static void main(String[] args){

        Scanner input = new Scanner(System.in);

        int action;

        bankJava myJavaBank = new bankJava(); //creating the bank


        do{

        System.out.println("Choose Action: ");
        System.out.println("(1) Withdraw");
        System.out.println("(2) Deposit");
        System.out.println("(3) Balance Inquiry");
        System.out.println("(4) Exit");
        action = input.nextInt();


        switch(action){



        //---------WITHDRAW------------//
        case 1 :

            System.out.println("******Withdraw******");
            myJavaBank.withdraw(); //withdrawing from it
            System.out.println("***************************");


            break;

        //---------DEPOSIT------------//
        case 2 :

            System.out.println("******Deposit******");
            myJavaBank.deposit(); //deposit from it
            System.out.println("***************************");
            break;

        //-----------Balance Inquiry-------//
        case 3 :

            System.out.println("******Balance Inquiry******");
            myJavaBank.accBalance();
            //You don't post this method but I suppose it will refer to the same bank
            System.out.println("***************************");

            break;

        case 4 :

            System.out.println("Thank you for choosing our bank!");
            break;

        default :

            System.out.println("Invalid action.");
            break;

        } 
        }while(action != 4);

    }


}

现在应该可以工作了。使用您的代码，您有4个不同的银行，一个仅用于存款，一个仅用于提款，依此类推。因此，一家银行将继续增加资金，而另一家银行将继续减少负数。

将 amount 参数设置为JavaBank参数，应在每个方法中添加局部变量，以便它不定义Bank。

类似

public class bankJava 
{

Scanner input = new Scanner(System.in);


double balance;

public void withdraw() 
{

    System.out.println("Enter amount: ");
    double amount = input.nextInt();

    balance = balance - amount;


}

public void deposit()
{

    System.out.println("Enter amount: ");
    double amount = input.nextInt();
    balance = balance + amount;

}

我还建议将input.nextInt()更改为input.nextDouble()，以便将 amount 创建为两倍。

如果您没有看到“余额查询”是因为显然您的accBalance（）方法为空。像这样编辑它：

public void accBalance(){
System.out.println("Your balance is: "+this.balance);
}

Answer 2

import java.util.Scanner;

public class BankJava {

    double balance = 0;
    double amount;

    public void withdraw(int amount) {

        balance = balance - amount;

    }

    public void deposit(int amount) {

        balance = balance + amount;
    }

    public double showBalance() {
        return balance;
    }


    public static void main(String[] args) {
        BankJava bank = new BankJava();
        Scanner input = new Scanner(System.in);
        int action;
        int amount;
         do{

                System.out.println("Choose Action: ");
                System.out.println("(1) Withdraw");
                System.out.println("(2) Deposit");
                System.out.println("(3) Balance Inquiry");
                System.out.println("(4) Exit");
                action = input.nextInt();
                switch(action){
                //---------WITHDRAW------------//
                case 1 :

                    System.out.println("******Withdraw******");
                    System.out.println("enter amount:");
                    amount = input.nextInt();
                    bank.withdraw(amount);
                    System.out.println("***************************");
                    System.out.println("Your balance is now: " + bank.showBalance());
                    break;

                //---------DEPOSIT------------//
                case 2 :

                    System.out.println("******Deposit******");
                    System.out.println("enter amount:");
                    amount = input.nextInt();
                    bank.deposit(amount);
                    System.out.println("***************************");
                    System.out.println("Your balance is now: " + bank.showBalance());
                    break;

                //-----------Balance Inquiry-------//
                case 3 :

                    System.out.println("******Balance Inquiry******");
                    System.out.println("Your balance is: " + bank.showBalance());
                    System.out.println("***************************");

                    break;

                case 4 :

                    System.out.println("Thank you for choosing our bank!");
                    break;

                default :

                    System.out.println("Invalid action.");
                    break;

                } 
                }while(action != 4);

            }
    }

尝试一下此代码，与您的代码进行比较，找出问题所在，也可以问我是否需要更多帮助

我如何在进行取款和存款（取款，存款，余额查询）之后更新余额

2 个答案: