取款和存款后如何更新余额（取款，存款，余额查询）java

Question

我在 java 有作业。我的任务是建立一家可以提取、存款和查询余额的银行。我的问题是我无法在存款和取款后更新我的余额......我已经尝试了我能做的一切但仍然无法理解逻辑。有人可以帮助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()
    {


    }



}

--------------------------------主要------------ ----------------------

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

为什么要实例化 4 个不同的 JavaBank？为每个操作执行此操作，您将在不同的对象中执行每个方法。如果我很好地理解你的问题，我认为你可以在同一个对象中轻松解决你的问题。

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);

    }


}

现在应该可以了。使用您的代码，您有 4 家不同的银行，一家仅用于存款，一家仅用于提款等。所以一家银行会继续加钱，一家会继续减钱。

此外 amount 参数不应该是 JavaBank 参数，在每个方法中嵌入一个局部变量，这样它就不会定义 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()，这样您就可以将金额创建为双倍金额。

如果您没有看到余额查询，那是因为显然您的 accBalance() 方法是空白的。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);

            }
    }

试试这个代码，与你的比较，找出问题所在，如果你需要更多帮助，也可以问我

取款和存款后如何更新余额（取款，存款，余额查询）java

how can i update balance after doing withdrawal and deposits(withdraw,deposit,balance inquiry) java

java

bank