java - 取款和存款后如何更新余额(取款，存款，余额查询)java

Question

我有一个java作业。我的任务是建立一个可以取款、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

为什么要建立 4 个不同的 JavaBank？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，另一家仅用于取款，依此类推。所以一家银行会继续加钱，一家银行会继续减钱。

此外，amount 参数不应该是 JavaBank 参数，而是在每个方法中添加一个局部变量，这样它就不会定义 Bank。

类似的东西

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()，以便将金额创建为 double .

如果您没有看到余额查询，显然是因为您的 accBalance() 方法为空。像这样编辑它:

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