在atm项目中实现例外

Question

我有一项任务是创建一个小型银行业务计划，该计划可以保留两个帐户，定期存款和储蓄。然而，当我准备完成一个粗略的版本时，我读到了提示，我想用我们了解到的那天我生病的那一天，例外。

我不清楚如何使用异常，或者如果我应该制作自己的异常类。我想要一个例外，以便在程序中的任何时候，如果输入以'q'或'Q'开头的内容，程序退出并结束。另一项规定是，如果储蓄低于25美元以冻结帐户。我想象例外对于这个功能来说是理想的。

public abstract class BankAccount { 

    int balance; 
    int deposits; 
    int withdrawals; 
    int annualInterestRate; 
    int charges; 

    public void _BankAccount(int newBalance, int newInterest) { 
     balance = newBalance; 
     annualInterestRate = newInterest; 
    } 

    public void Deposit(int newDeposit) { 
     balance = balance + newDeposit; 
     deposits++; 
    } 

    public void Withdraw(int newWithdraw) { 
     balance = balance - newWithdraw; 
     withdrawals++; 
    } 

    public void calcInterest() { 
     int monthlyInterestRate = (annualInterestRate/12); 
     int monthlyInterest = balance * monthlyInterestRate; 
     balance = balance + monthlyInterest; 
    } 

    public void monthlyProcess() { 
     balance = balance - charges; 
     calcInterest(); 
     deposits = 0; 
     withdrawals = 0; 
    } 
} 

public class SavingsAccount extends BankAccount { 

    boolean status; 

    public void savingWithdraw(int newWithdraw) { 
     if (balance < 25) { 
      System.out.println("Error – Not enough funds."); 
     } else { 
      Withdraw(newWithdraw); 
     } 
    } 

    public void savingDeposit(int newDeposit) { 
     if (balance < 25) { 
      Deposit(newDeposit); 
      System.out.println("Savings account is now active."); 
     } else { 
      Deposit(newDeposit); 
     } 
    } 

    public void savingMonthlyProcess() { 
     if (withdrawals > 4) { 
      charges = ((withdrawals - 4) * 1); 
      balance = balance - ((withdrawals - 4) * 1); 
      if (balance < 25) { 
       System.out.println("Savings account is now inactive."); 
      } 
     } 
    } 
} 

public static void main(String[] args) { 
    Scanner in = new Scanner(System.in); 
    String choice; 
    int num = 0; 
    boolean quit = false; 
    do { 
     System.out.println("Which account would you like to access, regular or savings?:"); 
     choice = in.nextLine(); 
     if (choice.equals("regular")) { 
      num = 0; 
     } 
     if (choice.equals("savings")) { 
      num = 1; 
     } 
     switch (num) { 
      case 0: 
       System.out.println("What action do you wish to perform \n(Withdraw, deposit, monthly processing)?:"); 
       choice = in.nextLine(); 
       if (choice.equals("withdraw")) { 
        num = 0; 
       } 
       if (choice.equals("deposit")) { 
        num = 1; 
       } 
       if (choice.equals("monthly processing")) { 
        num = 2; 
       } 
       switch (num) { 
        case 0: 
         System.out.println("Enter amount to withdraw:"); 
         Withdraw(in.nextInt()); 
        case 1: 
         System.out.println("Enter amount to withdraw:"); 
         Deposit(in.nextInt()); 
        case 2: 
         MonthlyProcess(); 
       } 
      case 1: 
       System.out.println("What action do you wish to perform \n(Withdraw, deposit, monthly processing)?:"); 
       choice = in.nextLine(); 
       if (choice.equals("withdraw")) { 
        num = 0; 
       } 
       if (choice.equals("deposit")) { 
        num = 1; 
       } 
       if (choice.equals("monthly processing")) { 
        num = 2; 
       } 
       switch (num) { 
        case 0: 
         System.out.println("Enter amount to withdraw:"); 
         savingsWithdraw(in.nextInt()); 
        case 1: 
         System.out.println("Enter amount to withdraw:"); 
         savingsDeposit(in.nextInt()); 
        case 2: 
         savingMonthlyProcess(); 
       } 

     } 
    } 


} 

}

Answer 1

异常被用来处理所不希望的情况。就你而言，你可以使用内置的异常类来处理大多数运行时异常，但是可以使用自定义消息。

另一项规定是，如果储蓄低于25美元冻结帐户。

对于上述情况，您可以很好地创建一个新的异常类，并使用用户定义的错误消息来处理此异常。

您可以阅读Exception handling in java的更多信息。