Question

我有一个家庭作业问题，我必须为银行账户中的每笔交易扣除一笔费用，该费用超过分配的免费交易数量。我的问题是我的Math.max不适用于deductMonthlyCharge课程，而不是仅在交易超过分配金额时才收取费用，该计划正在收取每笔交易的费用。我不知道如何解决这个问题。此外，我应该在每个月后重置交易计数。我不知道该怎么做。如果有人能够朝着正确的方向推动我，那将非常感谢。

这是我的BankAccount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

您从未在非默认构造函数中设置freeTransactions，因此默认为0：

public BankAccount(double initialBalance)

你可以像这样调用你的默认构造函数：

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

以便调用语句freeTransactions = 5;。

Answer 2

你错过了一个构造函数的几行。

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

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

Answer 3

Math.max(a,b)是正确的，并返回更大的值。如果有计算费用，您可能希望将方法更改为仅计算费用，因此没有剩余的免费交易。

顺便说一下。 freeTransactions和fee应通过声明或构造来设置。

public double deductMonthlyCharge()
   {
       double transCount = Math.max(transactionCount, freeTransactions) - freeTransactions;
       double fee = 0;
       if (transCount > 0) fee = 2.00 * transCount;
       return fee;
   }

或者我错了？

Answer 4

我会这样写，而不是尝试使用数学。

if (transactionCount <= freeTransactions)
   return 0;
return 2 * (transactionCount - freeTransactions);

将Math.max用于BankAccount类

4 个答案: