MSVB Example Application: College Park Auto Parts

	Microsoft Visual Basic Example Application: College Park Auto Parts

Introduction

In our introduction to collections, we saw how to create a collection class. Rather than creating your own collection, in our review of built-in collection classes, we studied the ArrayList and the generic List<> classes. In this exercise, we apply these concepts to create an application.

This is an application used by a (fictitious, of course) company that sells auto parts. When using the application, the user can select the car year, the make, and the model. The user also has the ability to specify the category of the item the customer wants. This makes it easy to locate the part.

Practical Learning: Creating the Application

Start Microsoft Visual Basic and create a new Windows Forms Application named CollegeParkAutoParts1
To create a dialog box, on the main menu, click Project -> Add Windows Form...
Set the name to MakeEditor and click Add

Design the form as follows:

Control	Text	Name	Other Properties
Label	&Make:
TextBox		txtMake	Modifiers: Public
Button	OK	btnOK	DialogResult: OK
Button	Cancel	btnCancel	DialogResult: Cancel

Form Property

Value

FormBorderStyle

FixedDialog

Text

Make Editor

StartPosition

CenterScreen

AcceptButton

btnOK

CancelButton

btnCancel

MaximizeBox

False

MinimizeBox

False

ShowInTaskbar

False

To create a dialog box, on the main menu, click Project -> Add Windows Form...
Set the name to ModelEditor and click Add

Design the form as follows:

Control	Text	Name	Other Properties
Label	&Model:
TextBox		txtModel	Modifiers: Public
Button	OK	btnOK	DialogResult: OK
Button	Cancel	btnCancel	DialogResult: Cancel

Form Property

Value

FormBorderStyle

FixedDialog

Text

Model Editor

StartPosition

CenterScreen

AcceptButton

btnOK

CancelButton

btnCancel

MaximizeBox

False

MinimizeBox

False

ShowInTaskbar

False

To create a dialog box, in the Solution Explorer, right-click CollegeParkAutoParts2 -> Add -> Windows Form...
Set the name to CategoryEditor and click Add

Design the form as follows:

College Park Auto Parts: Category Editor

Control	Text	Name	Other Properties
Label	&Category:
TextBox		txtCategory	Modifiers: Public
Button	OK	btnOK	DialogResult: OK
Button	Cancel	btnCancel	DialogResult: Cancel

Form Property

Value

FormBorderStyle

FixedDialog

Text

Category Editor

StartPosition

CenterScreen

AcceptButton

btnOK

CancelButton

btnCancel

MaximizeBox

False

MinimizeBox

False

ShowInTaskbar

False

On the main menu, click Project -> Add Windows Form...
Set the Name to NewStoreItem and click Add

Design the form as follows:

Control	Text	Name	Other Properties
Label	&Year:
TextBox		txtItemNumber
Label	&Make:
ComboBox		cbxMakes
Button	New C&ategory...	btnNewMake
Label	M&odel:
ComboBox		cbxModels
Button	New Mo &del...	btnNewModel
Label	&Category:
ComboBox		cbxCategories
Button	New Ca&tegory	btnNewCategory
Label	&Unit Price:
TextBox	0.00	txtUnitPrice	TextAlign: Right
Label	Part #:
TextBox		txtPartNumber
Label	&Part Name:
TextBox		txtPartName
Button	Submit	btnSubmit
Button	Close	btnClose	DialogResult: Cancel

Form Property

Value

FormBorderStyle

FixedDialog

Text

College Park Auto -Parts: Part Editor

StartPosition

CenterScreen

MaximizeBox

False

MinimizeBox

False

ShowInTaskbar

False

Right-click the form and click View Code
In the Class Name combo box, select btnNewMake

In the Method Name combo box, select Click and implement the event as follows:

Private Sub btnNewMakeClick(ByVal sender As Object, 
                                 ByVal e As System.EventArgs) 
                                 Handles btnNewMake.Click
        Dim Editor As MakeEditor = New MakeEditor

        If Editor.ShowDialog() = DialogResult.OK Then
            If Editor.txtMake.Text.Length > 0 Then
                Dim strMake As String = Editor.txtMake.Text

                ' Make sure the category is not yet in the list
            If cbxMakes.Items.Contains(strMake) Then
                    MsgBox(strMake & " is already in the list")
                Else
                    ' Since this is a new category, add it to the combo box
                    cbxMakes.Items.Add(strMake)
                End If

                cbxMakes.Text = strMake
            End If
        End If
End Sub

In the Class Name combo box, select btnNewModel

In the Method Name combo box, select Click and implement the event as follows:

Private Sub btnNewModelClick(ByVal sender As Object, 
                                  ByVal e As System.EventArgs) 
                                  Handles btnNewModel.Click
        Dim Editor As ModelEditor = New ModelEditor

        If Editor.ShowDialog() = DialogResult.OK Then

            If Editor.txtModel.Text.Length > 0 Then
                Dim strModel As String = Editor.txtModel.Text

                ' Make sure the category is not yet in the list
            If cbxModels.Items.Contains(strModel) Then
                    MsgBox(strModel & " is already in the list")
                Else
                    ' Since this is a new category, add it to the combo box
                    cbxModels.Items.Add(strModel)
                End If

                cbxModels.Text = strModel
            End If
        End If
End Sub

In the Class Name combo box, select btnNewCategory

In the Method Name combo box, select Click and implement the event as follows:

Private Sub btnNewCategoryClick(ByVal sender As Object, 
                                     ByVal e As System.EventArgs) 
                                     Handles btnNewCategory.Click
        Dim Editor As CategoryEditor = New CategoryEditor

        If Editor.ShowDialog() = DialogResult.OK Then
            If Editor.txtCategory.Text.Length > 0 Then
                Dim strCategory As String = Editor.txtCategory.Text

                ' Make sure the category is not yet in the list
                If cbxCategories.Items.Contains(strCategory) Then
                    MsgBox(strCategory & " is already in the list")
                Else
                    ' Since this is a new category, add it to the combo box
                    cbxCategories.Items.Add(strCategory)
                End If

                cbxCategories.Text = strCategory
            End If
        End If
End Sub

Save the file
To create an icon, on the main menu, click Project -> Add New Item...
In the Templates list, click Icon File
Set the Name to cpap1 and click Add
Right-click the white area and click Delete Image Type
Design the 16x16, 16 colors version of the icon as follows:
On the main menu, click File -> Save cpap1.ico As
Select the bin\Debug folder of the current folder and click Save
On the main menu, click File -> Close
In the Solution Explorer, expand bin and expand Debug
In the Solution Explorer, right-click the Debug folder -> Add -> New Item...
In the Templates list, make sure Icon File is selected.
Set the Name to cpap2 and click Add
Right-click the white area and click Delete Image Type
Design the 16x16, 16 colors version of the icon as follows:
Save the file and close the icon window
In the Solution Explorer, right- click the Debug folder -> Add -> New Item...
In the Templates list, make sure Icon File is selected.
Set the Name to year1 and click Add
Right-click the white area and click Delete Image Type
Design the 16x16, 16 colors version of the icon as follows:
Save the file and close the icon window
In the Solution Explorer, right- click the Debug folder -> Add -> New Item...
In the Templates list, make sure Icon File is selected.
Set the Name to year2 and click Add
Right-click the white area and click Delete Image Type
Design the 16x16, 16 colors version of the icon as follows:
Save the file and close the icon window
In the Solution Explorer, right- click the Debug folder -> Add -> New Item...
In the Templates list, make sure Icon File is selected.
Set the Name to make1 and click Add
Right-click the white area and click Delete Image Type
Design the 16x16, 16 colors version of the icon as follows:
Save the file and close the icon window
In the Solution Explorer, right- click the Debug folder -> Add -> New Item...
In the Templates list, make sure Icon File is selected.
Set the Name to make2 and click Add
Right-click the white area and click Delete Image Type
Design the 16x16, 16 colors version of the icon as follows:
Save the file and close the icon window
In the Solution Explorer, right- click the Debug folder -> Add -> New Item...
In the Templates list, make sure Icon File is selected.
Set the Name to model1 and click Add
Right-click the white area and click Delete Image Type
Design the 16x16, 16 colors version of the icon as follows:
Save the file and close the icon window
In the Solution Explorer, right- click the Debug folder -> Add -> New Item...
In the Templates list, make sure Icon File is selected.
Set the Name to model2 and click Add
Right-click the white area and click Delete Image Type
Design the 16x16, 16 colors version of the icon as follows:
Save the file and close the icon window
In the Solution Explorer, right- click the Debug folder -> Add -> New Item...
In the Templates list, make sure Icon File is selected.
Set the Name to category1 and click Add
Right-click the white area and click Delete Image Type
Design the 16x16, 16 colors version of the icon as follows:
Save the file and close the icon window
In the Solution Explorer, right- click the Debug folder -> Add -> New Item...
In the Templates list, make sure Icon File is selected.
Set the Name to category2 and click Add
Right-click the white area and click Delete Image Type
Design the 16x16, 16 colors version of the icon as follows:
Save the file and close the icon window
In the Solution Explorer, right-click Form1.cs and click Rename
Type Central.vb and press Enter twice to display the Central form
From the Components section of the Toolbox, click ImageList and click the form
In the Properties window, click (Name) and type AutoPartsImages
Click the ellipsis button of the Images field
In the Image Collection Editor, click Add
Locate the folder that contains the icons you created and display it in the Look In combo box
Select cpap1.ico and click Open
In the same way, add the other pictures in the following order: cpap2.ico, year1.ico, year2.ico, make1.ico, make2.ico, model1.ico, model2.ico, category1.ico, and category1.ico
Click OK

Design the form as follows:

Control	Text	Name	Other Properties
Label	College Park Auto-Parts		Font: Times New Roman, 20.25pt, style=Bold ForeColor: Blue
Panel			Height: 2
GroupBox	Part Identification
TreeView		tvwAutoParts	ImageList: imgAutoParts
GroupBox	Available Parts
ListView		lvwAutoParts	FullRowSelect: True GridLines: True View: Details
Columns	(Name)	Text	TextAlign	Width
	colPartNumber	Part #
	colPartName	Part Name		300
	colUnitPrice	Unit Price	Right	80
GroupBox	Customer Order - Selected Parts
Label	Part #
Label	Part Name
Label	Unit Price
Label	Qty
Label	Sub Total
TextBox		txtPartNumber
TextBox		txtPartName
TextBox	0.00	txtUnitPrice	TextAlign: Right
TextBox	0	txtQuantity	TextAlign: Right
TextBox	0.00	txtSubTotal	TextAlign: Right
Button	Add/Select	btnAdd
ListView		lvwSelectedParts	FullRowSelect: True GridLines: True View: Details
Columns	(Name)	Text	TextAlign	Width
	colPartNumberSelected	Part #		45
	colPartNameSelected	Part Name		274
	colUnitPriceSelected	Unit Price	Right	58
	colQuantitySelected	Qty	Right	28
	colSubTotalSelected	Sub-Total	Right	58
GroupBox	Order Summary
Button	New Au&to Part...	btnNewAutoPart
Label	Receipt #:
TextBox		txtSave
Button	Save	btnSave
Label	Tax Rate:
TextBox	7.75	txtTaxRate	TextAlign: Right
Label	%
Label	Parts Total:
TextBox	0.00	txtPartsTotal	TextAlign: Right
Button	&New Customer Order	btnNewCustomerOrder
Label	Receipt #:
TextBox		txtOpen
Button	Save	btnSave
Label	Tax Amount:
TextBox	0.00	txtTaxAmount	TextAlign: Right
Label	Order Total:
TextBox	0.00	txtOrderTotal	TextAlign: Right
Button	Close	btnClose

Right-click the table and click Form View
In the Class Name combo box, select lvwAutoParts

In the Method Name combo box, select DoubleClick and implement the event as follows:

Private Sub lvwAutoPartsDoubleClick(ByVal sender As Object, 
                                         ByVal e As System.EventArgs) 
                                         Handles lvwAutoParts.DoubleClick
        Dim lviAutoPart As ListViewItem = lvwAutoParts.SelectedItems(0)

        If (lvwAutoParts.SelectedItems.Count = 0) Or 
           (lvwAutoParts.SelectedItems.Count > 1) Then
            Exit Sub
        End If

        txtPartNumber.Text = lviAutoPart.Text
        txtPartName.Text = lviAutoPart.SubItems(1).Text
        txtUnitPrice.Text = lviAutoPart.SubItems(2).Text

        txtQuantity.Text = "1"
        txtSubTotal.Text = lviAutoPart.SubItems(2).Text

        txtQuantity.Focus()
End Sub

In the Class Name combo box, select txtUnitPrice

In the Method Name combo box, select Leave and implement the event as follows:

Private Sub txtUnitPriceLeave(ByVal sender As Object, 
                                   ByVal e As System.EventArgs) 
                                   Handles txtUnitPrice.Leave, 
                                           txtQuantity.Leave
        Dim UnitPrice As Double
        Dim Quantity As Integer
        Dim SubTotal As Double

        Try
            UnitPrice = CDbl(txtUnitPrice.Text)
        Catch Exc As FormatException
            MsgBox("Invalid Unit Price!")
        End Try

        Try
            Quantity = CInt(txtQuantity.Text)
        Catch Exc As FormatException
            MsgBox("Invalid Quandtity!")
        End Try

        SubTotal = UnitPrice * Quantity
        txtSubTotal.Text = FormatNumber(SubTotal)
End Sub

Public Sub CalculateOrder()
        ' Calculate the current total order and update the order
        Dim PartsTotal As Double
        Dim TaxRate As Double
        Dim TaxAmount As Double
        Dim OrderTotal As Double
        Dim SubItem As ListViewItem.ListViewSubItem
        Dim lviAutoPart As ListViewItem

        For Each lviAutoPart In lvwSelectedParts.Items
            SubItem = lviAutoPart.SubItems(4)
            PartsTotal = PartsTotal + CDbl(SubItem.Text)
        Next

        Try
            TaxRate = CDbl(txtTaxRate.Text) / 100
        Catch Exc As FormatException
            MsgBox("Invalid Tax Rate")
        End Try

        TaxAmount = PartsTotal * TaxRate
        OrderTotal = PartsTotal + TaxAmount

        txtPartsTotal.Text = FormatNumber(PartsTotal)
        txtTaxAmount.Text = FormatNumber(TaxAmount)
        txtOrderTotal.Text = FormatNumber(OrderTotal)
End Sub

In the Class Name combo box, select lvwSelectedParts

In the Method Name combo box, select DoubleClick and implement the event as follows:

Private Sub lvwSelectedPartsDoubleClick(ByVal sender As Object, 
                                         ByVal e As System.EventArgs) 
                                         Handles lvwSelectedParts.DoubleClick
        Dim lviSelectedPart As ListViewItem = lvwSelectedParts.SelectedItems(0)

        If (lvwSelectedParts.SelectedItems.Count = 0) Or 
            (lvwSelectedParts.SelectedItems.Count > 1) Then
            Exit Sub
        End If

        txtPartNumber.Text = lviSelectedPart.Text
        txtPartName.Text = lviSelectedPart.SubItems(1).Text
        txtUnitPrice.Text = lviSelectedPart.SubItems(2).Text
        txtQuantity.Text = lviSelectedPart.SubItems(3).Text
        txtSubTotal.Text = lviSelectedPart.SubItems(4).Text

        lvwSelectedParts.Items.Remove(lviSelectedPart)
        CalculateOrder()
End Sub

In the Solution Explorer, right-click CollegeParkAutoParts1 -> Add -> Class...
Set the name to PartDescription and press Enter

To create a class that can hold a structured item of a list, change the class as follows:

<Serializable()> Public Class PartDescription
    ' These members will be used to define a car part
    Private ID As Long
    Private yr As Integer
    Private mk As String
    Private mdl As String
    Private cat As String
    Private name As String
    Private price As Double

    Public Sub New()
        ID = 0
        yr = 1960
        mk = ""
        mdl = ""
        name = "Unknown"
        price = 0.0
    End Sub

    Public Sub New(ByVal code As Long, ByVal year As Integer, 
                   ByVal make As String, ByVal model As String, 
                   ByVal type As String, ByVal desc As String, 
                   ByVal UPrice As Double)

        ID = code
        yr = year
        mk = make
        mdl = model
        cat = type
        name = desc
        price = UPrice
    End Sub

    Public Property PartNumber() As Long
        Get
            Return ID
        End Get
        Set(ByVal value As Long)
            ID = value
        End Set
    End Property

    Public Property Year() As Integer
        Get
            Return yr
        End Get
        Set(ByVal value As Integer)
            yr = value
        End Set
    End Property

    Public Property Make() As String
        Get
            Return mk
        End Get
        Set(ByVal value As String)
            mk = value
        End Set
    End Property

    Public Property Model() As String
        Get
            Return mdl
        End Get
        Set(ByVal value As String)
            mdl = value
        End Set
    End Property

    Public Property Category() As String
        Get
            Return cat
        End Get
        Set(ByVal value As String)
            cat = value
        End Set
    End Property

    Public Property PartName() As String
        Get
            Return name
        End Get
        Set(ByVal value As String)
            name = value
        End Set
    End Property

    Public Property UnitPrice() As Double
        Get
            Return price
        End Get
        Set(ByVal value As Double)
            price = value
        End Set
    End Property

    Public Overrides Function ToString() As String
        Return PartNumber & " " & 
               CStr(Year) & " " & 
               Make & " " & 
               Model & " " & 
               Category & " " & 
               PartName & " " & 
               UnitPrice
    End Function
End Class

In the Solution Explorer, right-click CollegeParkAutoParts3 -> Add -> Class...
Set the name to PartOrdered and press Enter

To create another class independent for a list, change the document as follows:

<Serializable()> Public Class PartOrdered
    Public PartNumber As Long
    Public PartName As String
    Public UnitPrice As Double
    Public Quantity As Integer
    Public SubTotal As Double
End Class

Save all
In the Solution Explorer, right-click NewStoreItem and click View Code

Add the following lines:

Imports System.IO
Imports System.Runtime.Serialization.Formatters.Binary

Public Class NewStoreItem
    Private ListOfAutoParts As List(Of PartDescription)

In the Class Name combo box, select btnSubmit

In the Method Name combo box, select Click and implement the event as follows:

Private Sub btnSubmitClick(ByVal sender As Object, 
                                ByVal e As System.EventArgs) 
                                Handles btnSubmit.Click
        Dim stmAutoParts As FileStream
        Dim bfmAutoParts As BinaryFormatter = New BinaryFormatter

        ' If this directory doesn't exist, create it
        Directory.CreateDirectory("C:\College Park Auto Parts")
        ' This is the file that holds the list of items
        Dim FileName As String = "C:\College Park Auto Parts\Parts.prs"

        ' Create a random number that will be used to identify the item
        Dim RndNumber As Random = New Random()
        txtPartNumber.Text = RndNumber.Next(100000, 999999).ToString()

        ' Make sure the user had selected a make
        If cbxYears.Text.Length = 0 Then
            MsgBox("You must specify the year")
            cbxYears.Focus()
            Exit Sub
        End If

        ' Make sure the user had selected a make
        If cbxMakes.Text.Length = 0 Then
            MsgBox("You must specify the car name")
            cbxMakes.Focus()
            Exit Sub
        End If

        ' Make sure the user had selected a model
        If cbxModels.Text.Length = 0 Then
            MsgBox("You must specify the model of the car")
            cbxModels.Focus()
            Exit Sub
        End If

        ' Make sure the user had selected the part category
        If cbxCategories.Text.Length = 0 Then
            MsgBox("You must specify the part's category")
            cbxCategories.Focus()
            Exit Sub
        End If

        ' Make sure the user had entered a name/description
        If txtPartName.Text.Length = 0 Then
            MsgBox("You must enter the name (or a " & 
                            "short description) for the part")
            txtPartName.Focus()
            Exit Sub
        End If

        ' Make sure the user had typed a price for the item
        If txtUnitPrice.Text.Length = 0 Then
            MsgBox("You must enter the price of the item")
            txtUnitPrice.Focus()
            Exit Sub
        End If

        ' Before saving the new part, find out if there was
        ' already a file that holds the list of parts
        ' If that file exists, open it and store its parts 
        ' in our lstParts variable
        If File.Exists(FileName) Then
            stmAutoParts = New FileStream(FileName, 
                                          FileMode.Open, 
                                          FileAccess.Read, 
                                          FileShare.Read)

            Try
                ' Retrieve the list of items from file
                ListOfAutoParts = 
			CType(bfmAutoParts.Deserialize(stmAutoParts),  
                                        List(Of PartDescription))
            Finally

                stmAutoParts.Close()
            End Try
        End If

        ' Create the part
        Dim Part As PartDescription = New PartDescription
        Part.PartNumber = CLng(txtPartNumber.Text)
        Part.Year = CInt(cbxYears.Text)
        Part.Make = cbxMakes.Text
        Part.Model = cbxModels.Text
        Part.Category = cbxCategories.Text
        Part.PartName = txtPartName.Text
        Part.UnitPrice = CDbl(txtUnitPrice.Text)

        ' Call the Add method of our collection class to add the part
        ListOfAutoParts.Add(Part)

        ' Save the list
        stmAutoParts = New FileStream(FileName, 
                                      FileMode.Create, 
                                      FileAccess.Write, 
                                      FileShare.Write)

        Try
            bfmAutoParts.Serialize(stmAutoParts, ListOfAutoParts)

            ' After saving the item, reset the form
            cbxYears.Text = ""
            cbxMakes.Text = ""
            cbxModels.Text = ""
            cbxCategories.Text = ""
            txtPartName.Text = ""
            txtUnitPrice.Text = "0.00"
            txtPartNumber.Text = RndNumber.Next(100000, 999999).ToString()
        Finally
            stmAutoParts.Close()
        End Try
End Sub

In the Solution Explorer, right-click Central.vb and click View Code

Add the following namespaces in the top section of the file and declare the two variables:

Imports System.IO
Imports System.Runtime.Serialization.Formatters.Binary

Public Class Central
    Private iFileName As Integer
    Private ListOfAutoParts As List(Of PartDescription)

In the Class Name combo box, select btnSaveCustomerOrder

In the Method Name combo box, select Click and implement the event as follows:

Private Sub btnSaveClick(ByVal sender As Object, 
                              ByVal e As System.EventArgs) 
                              Handles btnSave.Click
        Dim i As Integer
        Dim Part As PartsOrdered
        Dim bfmCustomerOrder As BinaryFormatter = New BinaryFormatter()

        ' We will store our files in the following folder    
        Dim strDirectory As String = "C:\College Park Auto Parts\Receipts"
        Dim DirInfo As DirectoryInfo = New DirectoryInfo(strDirectory)

        Dim strFilename As String = strDirectory & "\" & txtSave.Text & ".cap"

        Dim ListOfOrderedParts As List(Of PartsOrdered)

        If lvwSelectedParts.Items.Count = 0 Then
            Exit Sub
        Else

            ListOfOrderedParts = New List(Of PartsOrdered)

            For i = 0 To lvwSelectedParts.Items.Count - 1

                Part = New PartsOrdered

                Part.PartNumber = CLng(lvwSelectedParts.Items(i).Text)
                Part.PartName = lvwSelectedParts.Items(i).SubItems(1).Text
                Part.UnitPrice = 
		    CDbl(lvwSelectedParts.Items(i).SubItems(2).Text)
                Part.Quantity = 
		    CInt(lvwSelectedParts.Items(i).SubItems(3).Text)
                Part.SubTotal = CDbl(lvwSelectedParts.Items(i).SubItems(4).Text)
                ListOfOrderedParts.Add(Part)
            Next

            Dim stmCustomerOrder As FileStream = New FileStream(strFilename, 
                                                                FileMode.Create)

            Try
                bfmCustomerOrder.Serialize(stmCustomerOrder, ListOfOrderedParts)
            Finally
                stmCustomerOrder.Close()
            End Try
        End If
End Sub

Save all
In the Solution Explorer, right-click NewStoreItem.vb and click View Code
In the Class Name combo box, select cbxMakes

In the Method Name combo box, select SelectedIndexChanged and implement its event as follows:

Private Sub cbxMakesSelectedIndexChanged(ByVal sender As Object, 
                                          ByVal e As System.EventArgs) 
                                          Handles cbxMakes.SelectedIndexChanged
    cbxModels.Text = ""
    cbxModels.Items.Clear()
    Dim Part As PartDescription

    For Each Part In ListOfAutoParts
        If Part.Make = cbxMakes.Text Then
            If Not cbxModels.Items.Contains(Part.Model) Then
                cbxModels.Items.Add(Part.Model)
            End If
        End If
    Next
End Sub

In the Solution Explorer, right-click Central.vb and click View Code
In the Class Name, select btnAdd

In the Method Name combo box, select Click and implement the event as follows:

Private Sub btnAddClick(ByVal sender As Object, 
                             ByVal e As System.EventArgs) 
                             Handles btnAdd.Click
        Dim Part As PartDescription
        Dim lviSelectedPart As ListViewItem

        REM If the user didn't enter a part number, don't do anything
        If txtPartNumber.Text.Length = 0 Then
            MsgBox("There is no part to be added to the order")
            Exit Sub
        End If

        REM Since the user entered a part, check each item in the list of parts
        For Each Part In ListOfAutoParts
            REM If you find a part number that 
	    REM corresponds to the user's entry ...
            If Part.PartNumber = CLng(txtPartNumber.Text) Then
                REM ... display it in the Selected Parts list view
                lviSelectedPart = New ListViewItem(Part.PartNumber)

                lviSelectedPart.SubItems.Add(Part.PartName)
                lviSelectedPart.SubItems.Add(Part.UnitPrice)
                lviSelectedPart.SubItems.Add(txtQuantity.Text)
                lviSelectedPart.SubItems.Add(txtSubTotal.Text)
                lvwSelectedParts.Items.Add(lviSelectedPart)
            End If
        Next

        REM Update the order evaluation
        CalculateOrder()
End Sub

In the Class Name, select btnOpen

In the Method Name combo box, select Click and implement its event as follows:

Private Sub btnOpenClick(ByVal sender As Object, 
                              ByVal e As System.EventArgs) 
                              Handles btnOpen.Click
        Dim Part As PartOrdered
        Dim strFilename As String
        Dim lviReceiptPart As ListViewItem
        Dim ListOfReceipts As List(Of PartOrdered)
        Dim ReceiptsFormatter As BinaryFormatter = New BinaryFormatter()
        Dim StreamReceipts As FileStream = Nothing

        REM Identify the folder where the receipts are stored
        Dim strDirectory As String = "C:\College Park Auto Parts\Receipts"

        REM Get a reference to the receipts
        Dim dirReceipts As DirectoryInfo = New DirectoryInfo(strDirectory)
        REM Get the list of receipts in the folder
        Dim fleReceipts() As FileInfo = dirReceipts.GetFiles()

        REM Check that the user entered a receipt number
        REM If not, don't do anything
        If txtOpen.Text.Length = 0 Then
            MsgBox("You must enter a receipt number" & vbCrLf & 
                            "There is no receipt number to " & 
                            "open a customer's order")
            txtOpen.Focus()
            Exit Sub
        End If

        REM If no receipt was created before, let the user know
        If fleReceipts.Length = 0 Then
            MsgBox("There is no customer order to open")
            txtOpen.Focus()
            Exit Sub
        Else
            REM Since there is at least one receipt,
            REM get ready to use it/them
            lvwAutoParts.Items.Clear()
            lvwSelectedParts.Items.Clear()

            REM Create a file name using the path to the folder, 
            REM the receipt number, and the .cap extension
            strFilename = strDirectory & "\" & txtOpen.Text & ".cap"

            REM Check if there is a file with that receipt number
            If File.Exists(strFilename) Then
                Try
                    REM If so, retrieve the contents of that file
                 StreamReceipts = New FileStream(strFilename, FileMode.Open)
                    ListOfReceipts = 
		CType(ReceiptsFormatter.Deserialize(StreamReceipts),  
                                           List(Of PartOrdered))

                    REM And display the contents of that receipt number in 
                    REM the Selected Parts list view
                    For Each Part In ListOfReceipts
                        lviReceiptPart = New ListViewItem(Part.PartNumber)

                        lviReceiptPart.SubItems.Add(Part.PartName)
                      lviReceiptPart.SubItems.Add(FormatNumber(Part.UnitPrice))
                        lviReceiptPart.SubItems.Add(Part.Quantity)
                      lviReceiptPart.SubItems.Add(FormatNumber(Part.SubTotal))
                        lvwSelectedParts.Items.Add(lviReceiptPart)
                    Next
                Finally
                    StreamReceipts.Close()
                End Try

                REM Just in case, update the calculation
                CalculateOrder()
                REM In case the user will modify the file that was opened,
                REM put its receipt number in the Save text box
                txtSave.Text = txtOpen.Text
            Else
                REM Since it appears that the user 
		REM entered an invalid receipt number
                REM let him/her know
                MsgBox("There is no customer order with that receipt number")
            End If
        End If
End Sub

Save the file
In the Solution Explorer, right-click NewStoreItem.vb and click View Code
In the Class Name combo box, select (NewStoreItem Events)

In the Method Name combo box, select Load and implement the event as follows:

Private Sub NewStoreItemLoad(ByVal sender As Object, 
                                  ByVal e As System.EventArgs) 
                                  Handles Me.Load
        REM Since all values seem ready, prepare to process the item
        Dim i As Integer
        Dim Part As PartDescription
        Dim RndNumber As Random = New Random
        Dim StreamAutoParts As FileStream = Nothing
        Dim bfmAutoParts As BinaryFormatter = New BinaryFormatter

        ListOfAutoParts = New List(Of PartDescription)

        For i = DateTime.Today.Year + 1 To 1960 Step -1
            cbxYears.Items.Add(i)
        Next

        REM Create a random number that will be used to identify the item
        txtPartNumber.Text = RndNumber.Next(100000, 999999)

        REM This is the file that holds the list of parts
        Dim FileName As String = "C:\College Park Auto Parts\Parts.prs"

        If File.Exists(FileName) Then
            StreamAutoParts = New FileStream(FileName, 
                                                    FileMode.Open, 
                                                    FileAccess.Read, 
                                                    FileShare.Read)
            Try
                REM Retrieve the list of items from file
                ListOfAutoParts = 
		    CType(bfmAutoParts.Deserialize(StreamAutoParts),  
                                        List(Of PartDescription))

                REM Display the car manufacturers in the Make combo box
                For i = 0 To ListOfAutoParts.Count - 1
                    Part = CType(ListOfAutoParts(i), PartDescription)

                    If Not cbxMakes.Items.Contains(Part.Make) Then
                        cbxMakes.Items.Add(Part.Make)
                    End If
                Next

                REM Display the pats categories in the Category combo box
                For i = 0 To ListOfAutoParts.Count - 1
                    Part = CType(ListOfAutoParts(i), PartDescription)

                    If Not cbxCategories.Items.Contains(Part.Category) Then
                        cbxCategories.Items.Add(Part.Category)
                    End If
            Next
            Finally
                StreamAutoParts.Close()
            End Try
        End If
End Sub

In the Solution Explorer, right-click Central.vb and click View Code
In the Class Name combo box, select txtPartNumber

In the Method name combo box, select Leave and implement the event as follows:

Private Sub txtPartNumberLeave(ByVal sender As Object, 
                                    ByVal e As System.EventArgs) 
                                    Handles txtPartNumber.Leave
        Dim Part As PartDescription
        ' We will allow the user to enter a part number
        ' In the beginning, we assume that the user 
        ' had entered an invalid number
        Dim Found As Boolean = False
        ' This will represent the part found, if any
        Dim PartFound As PartDescription = Nothing

        ' After the user had entered a part number,
        ' check the whole list of parts
        For Each Part In ListOfAutoParts
            ' If you find a part that holds the number the user had entered
            If Part.PartNumber = CLng(txtPartNumber.Text) Then
                ' Mark that part
                PartFound = Part
                ' And update the flag that specifies 
		REM that the part has been found
                Found = True
            End If
            ' If the part number was not found, check the next
        Next ' If no part has that number, the found flag keeps marked as false

        ' If a part with that number was found...
        If Found = True Then
            ' Show the corresponding part name and unit price
            txtPartName.Text = PartFound.PartName
            txtUnitPrice.Text = FormatNumber(PartFound.UnitPrice)
            txtQuantity.Text = "1"
            txtSubTotal.Text = FormatNumber(PartFound.UnitPrice)
            ' Give focus to the quantity in case the user was to increase it
            txtQuantity.Focus()
        Else
            ' Since no part with that number was found,
            ' reset the text boxes
            txtPartName.Text = ""
            txtUnitPrice.Text = "0.00"
            txtQuantity.Text = "0"
            txtSubTotal.Text = "0.00"

            ' Let the user know that the part number that 
            ' was entered is not in the list
            MsgBox("There is no part with that number")
        End If
End Sub

Under the above End Sub line, create the following procedure:

Public Sub ShowAutoParts()
        Dim Years As Integer
        Dim NodeYear
        Dim NodeMake As TreeNode
        Dim NodeModel As TreeNode
        Dim Part As PartDescription
        Dim StreamAutoParts As FileStream
        Dim bfmAutoParts As BinaryFormatter = New BinaryFormatter

        tvwAutoParts.Nodes.Clear()

        Dim nodRoot As TreeNode = 
          tvwAutoParts.Nodes.Add("College Park Auto-Parts", 
                                 "College Park Auto-Parts", 0, 1)
        ' Show the years nodes
        For Years = DateTime.Today.Year + 1 To 1960 Step -1
            nodRoot.Nodes.Add(CStr(Years), CStr(Years), 2, 3)
        Next

        tvwAutoParts.SelectedNode = nodRoot
        ' Expand the root node
        tvwAutoParts.ExpandAll()

        ListOfAutoParts = New List(Of PartDescription)

        ' This is the file that holds the list of auto parts
        Dim Filename As String = "C:\College Park Auto Parts\Parts.prs"

        If File.Exists(FileName) Then
            StreamAutoParts = New FileStream(Filename, 
                                             FileMode.Open, 
                                             FileAccess.Read, 
                                             FileShare.Read)
            Try
                ' Retrieve the list of parts from file
                ListOfAutoParts = 
			CType(bfmAutoParts.Deserialize(StreamAutoParts),  
                                        List(Of PartDescription))

                ' Show the makes nodes
                For Each NodeYear In nodRoot.Nodes

                    Dim ListOfMakes As List(Of String) = New List(Of String)

                    For Each Part In ListOfAutoParts
                        If NodeYear.Text = Part.Year.ToString() Then
                            If Not ListOfMakes.Contains(Part.Make) Then
                                ListOfMakes.Add(Part.Make)
                            End If
                        End If
                    Next

                    For Each strMake As String In ListOfMakes
                        NodeYear.Nodes.Add(strMake, strMake, 4, 5)
                    Next
                Next

                ' Showing the models nodes
                For Each NodeYear In nodRoot.Nodes

                    For Each NodeMake In NodeYear.Nodes

                        Dim ListOfModels As List(Of String) = 
				New List(Of String)

                        For Each Part In ListOfAutoParts
                            If (NodeYear.Text = CStr(Part.Year)) And 
                                (NodeMake.Text = Part.Make) Then

                                If Not ListOfModels.Contains(Part.Model) Then
                                    ListOfModels.Add(Part.Model)
                                End If

                            End If
                        Next

                        For Each strModel As String In ListOfModels
                            NodeMake.Nodes.Add(strModel, strModel, 6, 7)
                        Next
                    Next
                Next

                ' Showing the categories nodes
                For Each NodeYear In nodRoot.Nodes
                    For Each NodeMake In NodeYear.Nodes
                        For Each NodeModel In NodeMake.Nodes
                            Dim ListOfCategories As 
				List(Of String) = New List(Of String)

                            For Each Part In ListOfAutoParts
                                If (NodeYear.Text = CStr(Part.Year)) And 
                                    (NodeMake.Text = Part.Make) And 
                                    (NodeModel.Text = Part.Model) Then

                           If Not ListOfCategories.Contains(Part.Category) Then
                                        ListOfCategories.Add(Part.Category)
                                    End If
                                End If
                            Next

                            For Each strCategory As String In ListOfCategories
                          NodeModel.Nodes.Add(strCategory, strCategory, 8, 9)
                            Next
                        Next
                    Next
                Next
            Finally
                StreamAutoParts.Close()
            End Try
        End If
End Sub

In the Class Name combo box, select btnNewAutoPart

In the Method Name combo box, select Click and implement the event as follows:

Private Sub btnNewAutoPartClick(ByVal sender As Object, 
                                     ByVal e As System.EventArgs) 
                                     Handles btnNewAutoPart.Click
        Dim Editor As NewStoreItem = New NewStoreItem

        If Editor.ShowDialog() = DialogResult.Cancel Then
            ShowAutoParts()
        End If
End Sub

In the Class Name combo box, select btnNewCustomerOrder

In the Method Name combo box, select Click and implement the event as follows:

Private Sub btnNewCustomerOrderClick(ByVal sender As Object, 
                                          ByVal e As System.EventArgs) 
                                          Handles btnNewCustomerOrder.Click
        ' We will store our files in the following folder    
        Dim strDirectory As String = "C:\College Park Auto Parts\Receipts"
        Dim dirInfo As DirectoryInfo = Directory.CreateDirectory(strDirectory)

        ' Get the list of files, if any, from our directory
        Dim ListOfFiles() As FileInfo = dirInfo.GetFiles()

        ' If there is no file in the directory,
        ' then we will use 1000 as the first file name
        If ListOfFiles.Length = 0 Then
            iFileName = 1000
        Else ' If there was at least one file in the directory
            ' Get a reference to the last file
            Dim LastFile As FileInfo = ListOfFiles(ListOfFiles.Length - 1)
            ' Get the name of the last file without its extension
            Dim fwe As String = 
		Path.GetFileNameWithoutExtension(LastFile.FullName)
            ' Increment the name of the file by 1
            iFileName = CInt(fwe) + 1
        End If

        txtSave.Text = iFileName.ToString()

        lvwAutoParts.Items.Clear()
        lvwSelectedParts.Items.Clear()
End Sub

In the Class Name combo box, select (Central Events)

In the Method Name combo box, select Load and implement the event as follows:

Private Sub CentralLoad(ByVal sender As Object, 
                             ByVal e As System.EventArgs) 
                             Handles Me.Load
        ShowAutoParts()
        btnNewCustomerOrderClick(sender, e)
End Sub

In the Class Name combo box, select tvwAutoParts

In the Method Name combo box, select NodeMouseClick and implement the event as follows:

Private Sub tvwAutoPartsNodeMouseClick(ByVal sender As Object, 
              ByVal e As System.Windows.Forms.TreeNodeMouseClickEventArgs) 
                                        Handles tvwAutoParts.NodeMouseClick
    Dim Part As PartDescription
    Dim lviAutoPart As ListViewItem
    Dim NodeClicked As TreeNode = e.Node

    If NodeClicked.Level = 4 Then
        lvwAutoParts.Items.Clear()
    End If

    Try
        For Each Part In ListOfAutoParts
            If (Part.Category = NodeClicked.Text) And 
                (Part.Model = NodeClicked.Parent.Text) And 
                (Part.Make = NodeClicked.Parent.Parent.Text) And 
                (CStr(Part.Year) = NodeClicked.Parent.Parent.Parent.Text) Then
                lviAutoPart = New ListViewItem(Part.PartNumber)

                lviAutoPart.SubItems.Add(Part.PartName)
                lviAutoPart.SubItems.Add(FormatNumber(Part.UnitPrice))
                lvwAutoParts.Items.Add(lviAutoPart)
            End If
        Next
    Catch Exc As NullReferenceException

    End Try
End Sub

In the Class Name combo box, select btnClose

In the Method Name combo box, select Click and implement the event as follows:

Private Sub btnCloseClick(ByVal sender As Object, 
                               ByVal e As System.EventArgs) 
                               Handles btnClose.Click
        End
End Sub

Execute the application
Click the New Auto Part button and use the Part Editor to create a few parts (let the computer generate the part numbers)
Close the Part Editor
Create a few customer part orders and save them:
Close the forms and return to your programming environment
Execute the application again and open a previously saved order
Close the forms and return to your programming environment

Exercises

College Park Auto Parts

Open the CollegeParkAutoParts5 application from this lesson
Add a context menu for the Available Parts list view with the items: Select, Edit..., and Delete
Configure the context menu so that
1. If the user clicks Select, the behavior would be the same as if the user had double-clicked the item
2. If the user clicks Edit..., the Part Editor dialog box would display with the part in it. The user can then edit any part (year, make, model, category, part name, or unit price) except the part number. Then the user can save the changed part
3. If the user clicks Delete, a message box would warn the user and ask for confirmation with Yes/No answers. If the user clicks Yes, the part would be deleted from the list of auto parts
Configure the application so that the user can open an order, add new parts to it, or delete parts from it, then save the order
Extend the application so that the store can also sell items that are, or are not, car-related, such as books, t-shirts, cleaning items, maintenance items (steering oils, brake oils, etc), license plates, etc. Every item in the store should have an item number. The user can enter that item number in the Part # text box and press Tab or Enter. The corresponding item would then be retrieved from the database and displayed on the form. If there is no item with that number, a message box should let the user know


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