Question

我的问题是关于循环和异常。如果我运行这个程序，它将带我到1点，但它只是让我把一个字符串，然后停止。虽然我希望它继续下去，就像它最初那样。我做错了什么？

    while (true) {
        try {
    //From here I want to start everytime. Point 1
            System.out.println("Do you whish to deposit or withdraw money or end the transaction?");
            Scanner readerBankTransactions = new Scanner(System.in);
            String BankTransaction = readerBankTransactions.nextLine();

            if (BankTransaction.equalsIgnoreCase(Transactions.ENDTRANSACTION.toString())) {
                System.out.println("Thank you for using our service.");
                break; //The programma should terminate here

            } else {
                while (true) {
                    if (BankTransaction.equalsIgnoreCase(Transactions.DEPOSIT.toString())) {
                        System.out.println("How much do you whish to deposit?");
                        Scanner readerDeposit = new Scanner(System.in);
                        double deposit = readerDeposit.nextDouble();
                        rekening.deposit(deposit);
                        double balance = rekening.getBalance();
                        System.out.println("Your balance is now: " + balance);
                        readerDeposit.close();
                        break; //from here I want to start again at point 1.

                    } else if (BankTransaction.equalsIgnoreCase(Transactions.WITHDRAW.toString())) {
                        System.out.println("How much do you whish to withdraw?");
                        Scanner readerWithdraw = new Scanner(System.in);
                        double withdraw = readerWithdraw.nextDouble();
                        rekening.withdraw(withdraw);
                        double balance = rekening.getBalance();
                        System.out.println("Your balance is now: " + balance);
                        readerWithdraw.close();
                        break; //from here I want to start again at point 1.
                    } 
                    readerBankTransactions.close();
                    readerbankAccountNumber.close();
                }
            } continue;
        } catch (InputMismatchException | NumberFormatException exception1) {
            System.out.println("This is not what you should have put in");
        } catch (InsufficientFundsException exception2) {
            System.out.println("insufficientfunds!");
        } catch (MaximumWithdrawException exception3) {
            System.out.println("Maximum withdraw restriction!");
        }
    }
}

Answer 1

一些建议：

尽量避免使用while (true)后跟continue或break语句的模式。这使逻辑非常难以理解。
您应该在辅助方法中隔离一些逻辑。同样，这将使主逻辑更容易理解。
我不明白内部while循环的目的。你想在这里完成什么？

有了这个，这是我建议的重写：

do {
    try {
        String BankTransaction = getInitialSelection();

        if (isDepositRequest(BankTransaction)) {
            handleDeposit();
        } else if (isWithdrawalRequest(BankTransaction)) {
            handleWithdrawal();
        } 
    } catch (InputMismatchException | NumberFormatException exception1) {
        System.out.println("This is not what you should have put in");
    } catch (InsufficientFundsException exception2) {
        System.out.println("insufficientfunds!");
    } catch (MaximumWithdrawException exception3) {
        System.out.println("Maximum withdraw restriction!");
    }
} while (!isExitRequest(BankTransaction));
System.out.println("Thank you for using our service.");

这假设handleDeposit()，handleWithdrawal()的定义与原始代码中的相应代码相匹配。

另外，我假设了以下辅助方法：

private boolean isDepositRequest(String bankTransaction) {
    return Transactions.DEPOSIT.toString().equalsIgnoreCase(bankTransaction);
}

private boolean isWithdrawalRequest(String bankTransaction) {
    return Transactions.WITHDRAW.toString().equalsIgnoreCase(bankTransaction);
}

private boolean isExitRequest(String bankTransaction) {
    return Transactions.ENDTRANSACTION.toString().equalsIgnoreCase(bankTransaction);
}

Answer 2

您正在寻找的是被标记的休息时间。在https://docs.oracle.com/javase/tutorial/java/nutsandbolts/branch.html查看带标签的休息时间的信息为例如point1 :的外部while循环使用标签，并在要从第1点重新启动的位置使用break point1;

从java中的某个点重新启动

2 个答案: