Java Do-While 循环 - 如何使用 Q 选项结束程序

Question

所以我有这个简单的银行程序。它的主菜单是:

B - 检查余额

D - 存款

W - 取款

Q - 退出

它们的功能基本上就是它们的名字。有两种方法可以终止程序:通过输入“Q”和“N”。但是我对 Q - Quit 选项有疑问。这是源代码:

Scanner scan = new Scanner (System.in);
        
    char anotherTransact = 0, option;
    int balance = 100000, deposit = 0, withdraw = 0;
    
    do {
    System.out.println("\nWelcome to ABC BANK \n");
    
    System.out.println("B - Check for Balance");
    System.out.println("D - Make Deposit");
    System.out.println("W - Make Withdraw");
    System.out.println("Q - Quit");
    
    
        System.out.print("\nSelect an option : ");
        option = scan.next().charAt(0);
        
        
        if ((option == 'B') || (option == 'b')) {
            System.out.println("\nYour current balance is " +balance);
        }
        
        else if ((option == 'D') || (option == 'd')) {
            System.out.print("\nEnter amount to Deposit : ");
            deposit = scan.nextInt();
            if (deposit > 1 && deposit <= 500000) {
                System.out.println("Deposit Transaction is successfully completed.");
                balance = balance + deposit; 
            }
            else if (deposit > 500000) {
                System.out.println("Deposit Amount must not be greater than 500,000");
            }
            else {
                System.out.println("Deposit must be greater than zero");
            }
        }
        
        else if ((option == 'W') || (option == 'w')) {
            System.out.print("\nEnter amount to Withdraw : ");
            withdraw = scan.nextInt();
            if ((withdraw % 100 == 0 && withdraw < 150000)) {
                System.out.println("Withdrawal Transaction is successfully completed.");
                balance = balance - withdraw;
            }
            else if (withdraw > 150000) {
                System.out.println("Withdrawal Amount must not be greater then 150,000");
            }
            else if (withdraw < 0) {
                System.out.println("Withdrawal Amount must be greater than zero");
            }
            else {
                System.out.println("Withdawal Amount must be divisible by 100");
            }
        }
        
        else if ((option == 'Q') || (option == 'q')) 
            break;
        
        else {
            System.out.println("\nInvalid entry, enter any valid option : (B/D/W/Q)");
        }
        
        
        System.out.print("\nWant to Transact another (Y/N?) ");
        anotherTransact = scan.next().charAt(0);
        
        System.out.println("\n======================================================"); 
    }
    
    
    while ((anotherTransact == 'Y') || (anotherTransact =='y'));
        if ((anotherTransact == 'N' || anotherTransact == 'n')) {
            System.out.println("\nThank you for using this program!");
        }
        else {
            System.out.println("Invalid entry, entery any valid option : (Y/N)");
        }
    scan.close();

它的输出是这样的:

Welcome to ABC BANK 

B - Check for Balance
D - Make Deposit
W - Make Withdraw
Q - Quit

Select an option :

当我输入 Q 选项时，输出应该是这样的:

Welcome to ABC BANK 

B - Check for Balance
D - Make Deposit
W - Make Withdraw
Q - Quit

Select an option : Q
======================================================

Thank you for using this program!

但是当我输入它时，它会说这是一个无效的输入。我应该怎么做才能通过输入“Q”来结束程序？

Answer 1

您的 Q 实现是正确的，它将退出 do while 循环，但在 while 语句之后您有一个 if:

 if ((anotherTransact == 'N' || anotherTransact == 'n')) {
            System.out.println("\nThank you for using this program!");
        }
        else {
            System.out.println("Invalid entry, entery any valid option : (Y/N)");
        }

当您键入 Q 退出循环时 anotherTransact不等于 'N' 因此它将进入 else 并打印无效条目。如果我理解正确的话，在 while 语句之后你实际上并不需要:

 System.out.println("\n======================================================"); 
 System.out.println("\nThank you for using this program!");