Java 控制语句：为什么我的'；新余额'；当I'；记入贷方的费用'；然后'；支付信用卡'；两次？

我从一开始就试着阅读这本Java书，并在暑假做一些练习。我提出了这个问题： “（信用额度计算器）开发一个Java应用程序，确定 百货公司客户已超过收费帐户的信用限额……对于那些信用限额被超过的客户，程序应显示 “超出信用额度”消息

我的代码只有在我使用一次费用贷记时才有效。如果我再次使用Charge to Credit，我的新余额值将发生变化。例如：

这是我现在的问题。我的新余额应该仍然是22000，因为信用额度已经超过了。但现在是18000。我不知道哪里出了问题，所以我需要帮助

这是我的代码：

Customer.java

import java.util.Scanner;

public class Customer {

Scanner input = new Scanner (System.in);

int accNum,
    beginBal,
    creditLimit;

int itemsCharged,
    creditsPaid,
    newBalance;

int transaction;
String action;

public void start (){
    System.out.print("\nAccount Number: ");
    accNum = input.nextInt();

    System.out.print("Beginning Balance: ");
    beginBal = input.nextInt();

    System.out.print("Credit Limit: ");
    creditLimit = input.nextInt();

    transaction();
}

public void transaction (){

    boolean loop = true;
    while (loop){
        System.out.println("\n[1] Charge to Credit \n[2] Pay Credit \n[3] Balance Inquiry/Exit");
        System.out.print("Select Transaction #: ");

        transaction = input.nextInt();

        switch (transaction){
        case 1:
            System.out.print("\n--CHARGE TO CREDIT-- \nEnter amount: ");
            itemsCharged = input.nextInt();

            newBalance = beginBal + itemsCharged - creditsPaid;
            if (newBalance > creditLimit){
                System.err.println("Credit Limit Exceeded!");
                newBalance -= itemsCharged;
            } else {
                System.out.println("Amount charged.");
            }
            break;
        case 2:
            System.out.print("\n--PAY CREDIT-- \nEnter amount: ");
            creditsPaid = input.nextInt();

            newBalance = beginBal + itemsCharged - creditsPaid;
            if (creditsPaid > newBalance){
                System.err.println("Invalid Amount!");
                newBalance -= creditsPaid;
            } else {
                System.out.println("Payment posted!");
                newBalance = beginBal + itemsCharged - creditsPaid;
            }
            break;
        case 3:
            System.out.println("\n--BALANCE INQUIRY-- \nNew Balance: " + newBalance);
            restart();
            break;
        default:
            System.err.println("Invalid number!");
            transaction();
            break;
        }
    }
}

public void restart (){

    System.out.println("\nDo you have another transaction? [Y/N]");
    System.out.print("Select Action: ");

    boolean loop = true;
    while (loop){

        action = input.nextLine();

        switch (action){
        case "Y":
            start();
            break;
        case "N":
            System.err.println("Terminated.");
            System.exit(0);
            break;
        }
    }
}

} // end class

public class CreditLimitCal {
public static void main (String[] args){

    Customer cus = new Customer();

    cus.start();

}

}

CreditLimitCal.java

import java.util.Scanner;

public class Customer {

Scanner input = new Scanner (System.in);

int accNum,
    beginBal,
    creditLimit;

int itemsCharged,
    creditsPaid,
    newBalance;

int transaction;
String action;

public void start (){
    System.out.print("\nAccount Number: ");
    accNum = input.nextInt();

    System.out.print("Beginning Balance: ");
    beginBal = input.nextInt();

    System.out.print("Credit Limit: ");
    creditLimit = input.nextInt();

    transaction();
}

public void transaction (){

    boolean loop = true;
    while (loop){
        System.out.println("\n[1] Charge to Credit \n[2] Pay Credit \n[3] Balance Inquiry/Exit");
        System.out.print("Select Transaction #: ");

        transaction = input.nextInt();

        switch (transaction){
        case 1:
            System.out.print("\n--CHARGE TO CREDIT-- \nEnter amount: ");
            itemsCharged = input.nextInt();

            newBalance = beginBal + itemsCharged - creditsPaid;
            if (newBalance > creditLimit){
                System.err.println("Credit Limit Exceeded!");
                newBalance -= itemsCharged;
            } else {
                System.out.println("Amount charged.");
            }
            break;
        case 2:
            System.out.print("\n--PAY CREDIT-- \nEnter amount: ");
            creditsPaid = input.nextInt();

            newBalance = beginBal + itemsCharged - creditsPaid;
            if (creditsPaid > newBalance){
                System.err.println("Invalid Amount!");
                newBalance -= creditsPaid;
            } else {
                System.out.println("Payment posted!");
                newBalance = beginBal + itemsCharged - creditsPaid;
            }
            break;
        case 3:
            System.out.println("\n--BALANCE INQUIRY-- \nNew Balance: " + newBalance);
            restart();
            break;
        default:
            System.err.println("Invalid number!");
            transaction();
            break;
        }
    }
}

public void restart (){

    System.out.println("\nDo you have another transaction? [Y/N]");
    System.out.print("Select Action: ");

    boolean loop = true;
    while (loop){

        action = input.nextLine();

        switch (action){
        case "Y":
            start();
            break;
        case "N":
            System.err.println("Terminated.");
            System.exit(0);
            break;
        }
    }
}

} // end class

public class CreditLimitCal {
public static void main (String[] args){

    Customer cus = new Customer();

    cus.start();

}

}

这一行：

newBalance = beginBal + itemsCharged - creditsPaid;

不需要减去

贷方余额

，以前当用户付清部分余额时，您已经这样做了

newBalance每次只能修改一件事，因此对于案例1：

newBalance = newBalance + itemsCharged;

案例2：

newBalance = newBalance - creditsPaid;

---

但情况1也是如此。因此，如果我删除了它，那么我的新余额将越来越大，丢弃已支付的积分-/成功了，谢谢！但当我继续问“你有其他交易吗？”并输入另一个帐户编号时，开始余额为10000，信用额度为15000。然后我第一次在那个账户上记入贷方，上面写着“超出了贷方限额”。然后余额将是acc num 123中的上一个余额。@javanerd在start（）中您应该将newBal设置为beginBal，并重置其他值。现在一切都好了！非常感谢你！我现在可以安息了。英雄联盟