Savings Account using Class Modules Please use speaker notes for additional information!

Enter 100 in Transaction Amount and Click Deposit. Click on reset to transfer into balance. Enter amount and click on withdrawal. Click on reset to make opening balance.

SavAcct.vbp The deposit and withdrawal methods give the class the behaviors it needs to increase or decrease the balance. vTranAmt is the information passed to the deposit or withdrawal method. The Get and Let procedures are assign and retrieve property values. In this example, I do not want to assign to Balance so there is no Let.

SavAcct.vbp objSavAcct is dimensioned objSavAcct is instantiated Reset puts the current objSavAcct.Balance on the form using Get. The Deposit method receives wkTranAmt as vTranAmt and curBalance is changed. When I get the Balance it receives curBalance. “Occurs before the focus shifts to a (second) control that has its CausesValidation property set to True.” from Microsoft VB In fact, I am not really doing validation here, I am assigning.

SavAcct00.vbp

On the form an InputBox is used to take in the interest rate. The interest rate is now assigned to objSavAcct.IntRate where as vIntRate it is assigned to intIntRate.

SavAcct00.vbp

Private Sub cmdDpsit_Click() objSavAcct.Deposit wkTranAmt lblClsBal.Caption = objSavAcct.Balance cmdDpsit.Enabled = False cmdWthDrwl.Enabled = False cmdSetInt.Enabled = False cmdReset.Enabled = True End Sub Private Sub cmdDpsit_Click() objSavAcct.Deposit (wkTranAmt) lblClsBal.Caption = objSavAcct.Balance cmdDpsit.Enabled = False cmdWthDrwl.Enabled = False cmdSetInt.Enabled = False cmdReset.Enabled = True End Sub Both ways of coding work: The steps in coding the line objSavAcct.Deposit (wkTranAmt) The Deposit Method on the Class Module SavAcct.

SavAcct00.vbp In this example the validate makes sure that an amount was entered in the transaction box. However, problems develop if the entry is not made because the amount from the last transaction is used. A simple fix is shown below. Private Sub txtTrnAmt_Validate(Cancel As Boolean) If txtTrnAmt.Text <> "" Then wkTranAmt = txtTrnAmt.Text Else wkTranAmt = 0 End If End Sub

SavAcct01.vbp

RaiseEvent on insufficient funds.

SavAcct01.vbp If there are events that can be raised or triggered, the Dim statement needs to include the WithEvents clause.

SavAcct01.vbp Note that the code that puts out the msgbox saying insufficient funds is on the form. In this example, the validate checks to make sure a transaction amount was entered before transferring to wkTranAmt, and acts on the problem by setting to 0.

SavAcct01.vbp

SavAcct02.vbp

Public Sub Add(ByVal vAcctNbr As String, ByVal vIntRate As Integer) Dim NewSavAcct As New SavAcct With NewSavAcct.AccountNumber = vAcctNbr.IntRate = vIntRate colSavAccts.Add NewSavAcct,.AccountNumber End With 'The last line of the with block actually adds the NewSavAcct object to the savings 'accounts collection (SavAccts) and uses the AccountNumber as a key to the 'collection. You can retrieve that object from the collection by using the 'AccountNumber. End Sub Public Sub Remove(ByVal vAcctNbr As String) colSavAccts.Remove vAcctNbr End Sub Option Explicit 'A collection is a container object - it contains objects 'A collection can only have certain methods such as Add, Remove and Item Private colSavAccts As Collection Private Sub Class_Initialize() Set colSavAccts = New Collection End Sub This sets up a NewSavAcct which is an object of the SavAcct type and then adds it to the collection.

SavAcct02.vbp Public Function Item(ByVal vAcctNbr As String) As SavAcct Set Item = colSavAccts.Item(vAcctNbr) End Function 'Retrieves a particular object from the collection - this is the item method Option Explicit 'A collection is a container object - it contains objects 'A collection can only have certain methods such as Add, Remove and Item Private colSavAccts As Collection Private Sub Class_Initialize() Set colSavAccts = New Collection End Sub

SavAcct02.vbp Public Function NewEnum() Set NewEnum = colSavAccts.[_NewEnum] End Function

SavAcct02.vbp

Private Sub Form_Load() Set objSavAcct = New SavAcct Set colSavAccts = New SavAccts Call Initialize_Variables End Sub Public Sub Initialize_Variables() wkAcctNbr = "" wkBalance = 0 wkIntRate = 0 wkTranAmt = 0 txtAcctNbr.Text = "" lblOpnBal.Caption = "" lblClsBal.Caption = "" txtIntRate.Locked = False txtIntRate.Text = "" txtIntRate.Locked = True txtTrnAmt.Text = "" cmdDpsit.Enabled = True cmdWthDrwl.Enabled = True cmdReset.Enabled = True End Sub Instantiates the class modules SavAcct and SavAccts.

SavAcct02.vbp Private Sub txtIntRate_LostFocus() With txtIntRate.Appearance = 0.BackColor = &H F.BorderStyle = 0.Locked = True wkIntRate =.Text End With End Sub Private Sub cmdSetInt_Click() With txtIntRate.Appearance = 1.BackColor = &H BorderStyle = 1.Locked = False.SetFocus End With End Sub