10-1 Create an object inheritance hierarchy
TopsolutionsCreate an object inheritance hierarchy that a bank might use to represent customer’s bank accounts. Here are the specifications:
Class hierarchy:
- Create a Windows Form project.
- Add a Class “Account” (base class)anddefine the following members (Use the names given below):
- Instance variable balanceValue
Decimal type, stores the account balance
- Constructor Sub New
Need one Decimal parameter, initialize instance variable balanceValue using the parameter
- Property Balance
i. Define Get method to return balanceValue
ii. Define Set method
a) If paramater >=0.0, assign it to balanceValue
b) If paramater < 0.0, assign 0.0 to balanceValue.
- Sub Credit
i. Declared as overridable, so its derived classes could override it.
ii. Need one Decimal parameter
iii. Add this parameter to balanceValue
- Function Debit
i. Declared as overridable, so its derived classes could override it.
ii. Return a Boolean value
iii. Need one Decimal parameter
iv. If parameter > balanceValue, then just return False.
v. If parameter <= balanceValue, deduct parameter value from balanceValue and return True.
- Function ToString
i. Overrides Object’s ToString function
ii. Display account’s balance
iii. Please use the following definition in order to make testing easier.
'overrides ToString() to display account's information
Public Overrides Function ToString() As String
Return (String.Format("Balance: {0:C2}", Balance) & vbCrLf)
End Function
- Add Class “CheckingAccount” in the project, which inherits from class Account and includes the following members (Use the names given below):
- Instance variable transactionFee
Decimal type, stores the fee chared per transaction
- Constructor Sub New
i. Need two Decimal parameter
ii. Call base class’s constructor to set up base class part
iii. Initializes instance variable transactionFee using parameter’s value, if parameter < 0.0, initialize transactionFee to 0
- Property Fee
i. Define Get method to return transactionFee
ii. Define Set method
a) If paramater >=0.0, assign it to transactionFee
b) If paramater < 0.0, assign 0.0 to transactionFee.
- Sub Credit
i. Overrides base class’s Credit method.
ii. Call base class’s Credit method to perform credit transaction
iii. Deduct transactionFee from balance
- Function Debit
i. Overrides base class’s Debit method.
ii. Call base class’s Debit method to perform debit transaction
a) If the call returns True (successful), deduct transactionFee from balance and return True
b) If the call returns False (unsuccessful), do NOT deduct transactionFee from balance, just return False
- Function ToString
i. Overrides base class’s ToString function
ii. Display transaction fee and balance (calling base class’s method)
iii. Please use the following definition in order to make testing easier.
'overrides ToString() function to display checking's information
Public Overrides Function ToString() As String
Dim message As String
message = String.Format("Transaction fee: {0:C2}", Fee) & vbCrLf
message &= MyBase.ToString()
Return message
End Function
- Add another class “SavingsAccount” inproject, which inherits from base class “Account” and includs the following members(Use the names given below):
- Instance variable interestRate
Doublel type, stores the inerest rate of savings account
- Constructor Sub New
i. Need one Decimal parameter and one Double parameter
ii. Call base class’s constructor to set up base class part
iii. Initializes instance variable interestRate using the 2nd parameter’s value, if parameter < 0.0, initialize inerestRate to 0
- Property Rate
i. Define Get method to return interestRate
ii. Define Set method
a) If paramater >=0.0, assign it to interestRate
b) If paramater < 0.0, assign 0.0 to interestRate
- Function CalculateInterest
i. No parameter
ii. Return a decimal value
iii. interest = balance * interestRate / 12
iv. add this interest to balance
v. return the interest
- Function ToString
i. Overrides base class’s ToString function
ii. Display interest rate and interest amount, as well as balance (calling base class’s method)
iii. Please use the following definition in order to make testing easier.
'overrides ToString() function to display savingsAccount's information
Public Overrides Function ToString() As String
Dim message As String
message = String.Format("Interest rate: {0:p2}", Rate) & vbCrLf
message &= String.Format("Interest earned: {0:c2}", CalculateInterest()) & vbCrLf
message &= MyBase.ToString()
Return message
End Function
- Now, let’s test the classes, rename the file “Form1.vb” to “AccountTesterForm.vb”, create “Form_Load” event handler method, copy the following code and paste into the “Form_Load” method. Please do not modify the code in this tester in order to make testing easier.
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Dim account1 As New SavingsAccount(25, 0.03)
Dim account2 As New CheckingAccount(80, 1)
' display initial balance of each object
balanceLabel.Text = "account1" & vbCrLf & Convert.ToString(account1.GetType()) & vbCrLf & account1.ToString() & vbCrLf
balanceLabel.Text &= "account2" & vbCrLf & Convert.ToString(account2.GetType()) & vbCrLf & account2.ToString() & vbCrLf
' debit each account and show new balance
balanceLabel.Text &= "Attempting to debit account1 by $20.00." & vbCrLf
If account1.Debit(20) = True Then
balanceLabel.Text &= account1.ToString() & vbCrLf
End If
balanceLabel.Text &= "Attempting to debit account2 by $40.00." & vbCrLf
If account2.Debit(40) Then
balanceLabel.Text &= account2.ToString() & vbCrLf
End If
' credit each account and show new balance
balanceLabel.Text &= "Crediting $40.00 to account1." & vbCrLf
account1.Credit(40)
balanceLabel.Text &= account1.ToString() & vbCrLf
balanceLabel.Text &= "Crediting $65.00 to account2." & vbCrLf
account2.Credit(65)
balanceLabel.Text &= account2.ToString()
- Run your project in your computer, you should get the similar output, If not, please debug your code and run it again.
12 years ago
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accountapp.zip
