java - 将 Math.max 用于 BankAccount 类

Question

我有一个家庭作业问题，我必须为银行账户中超过分配的免费交易次数的每笔交易扣除费用。我的问题是我的 Math.max 不适用于 deductMonthlyCharge 类，程序不是仅在交易超过分配金额时才收取费用，而是收取每笔交易的费用。我不知道如何解决这个问题。另外，我应该在每个月后重置交易计数。我不知道该怎么做。如果有人可以将我推向正确的方向，将不胜感激。

这是我的银行账户代码:

public class BankAccount
{  
   private double balance;
   private double fee;
   private double freeTransactions;
   private double transactionCount;

   public BankAccount()
   {   
      balance = 0;
      fee = 5;
      freeTransactions = 5;
      transactionCount = 0;
   }

   public BankAccount(double initialBalance)
   {   
      balance = initialBalance;
      transactionCount = 0;
   }

   public void deposit(double amount)
   {  
      double newBalance = balance + amount;
      balance = newBalance;
      transactionCount++;
   }

   public void withdraw(double amount)
   {   
      double newBalance = balance - amount;
      balance = newBalance;
      transactionCount++;
   }

   public double getBalance()
   {   
      return balance;
   }    

   public void setTransFee(double amount)
   { 
       balance = amount+(balance-fee);
       balance = balance;
   }

   public void setNumFreeTrans(double amount) 
   {
       amount = freeTransactions;
   }

   public double deductMonthlyCharge()
   {
       double transCount = Math.max(transactionCount, freeTransactions);
       double fee = 2.00 * (transCount - freeTransactions);
       return fee;
   }
}

这是我的 BankAccountTester 代码:

public class BankAccountTester
    {
        private BankAccount rockdown;
        public static void main(String[] args) {
            BankAccount rockdown = new BankAccount(1000.0);
            rockdown.deposit(1000);
            rockdown.withdraw(500);
            rockdown.withdraw(400);
            rockdown.deposit(200);
            System.out.println(rockdown.getBalance()- rockdown.deductMonthlyCharge());

            rockdown.deposit(1000);
            rockdown.withdraw(500);
            rockdown.withdraw(400);
            rockdown.deposit(200);
            rockdown.deposit(500);
            System.out.println(rockdown.getBalance()- rockdown.deductMonthlyCharge());

            rockdown.deposit(1000);
            rockdown.withdraw(500);
            rockdown.withdraw(400);
            rockdown.deposit(200);
            rockdown.deposit(500);
            rockdown.withdraw(1000);
            System.out.println(rockdown.getBalance()- rockdown.deductMonthlyCharge());
        }
    } 

Answer 1

您永远不会在非默认 构造函数中设置freeTransactions，因此它默认为0:

public BankAccount(double initialBalance) 

您可以像这样从重载的构造函数中调用您的默认构造函数:

public BankAccount(double initialBalance) {   
   super();
   balance = initialBalance;
}

以便调用语句 freeTransactions = 5;。