Collection-Based Application: Altair Realtors

	Collection-Based Application: Altair Realtors

Introduction

A real estate company or agency is a business that presents or sells houses (properties) to prospective customers. This is an application that addresses some of the issues with a real estate company.

Practical Learning: Introducing the Collection Class

Start Microsoft Visual Studio
To create a new application, on the main menu, click File -> New Project...
In the middle list, click Windows Forms Application
Change the Name to AltairRealtors1
Click OK
To create a new class, on the main menu, click Project -> Add Class...
Set the Name to RealEstateProperty
Click Add

Change the file as follows:

<Serializable()>
Public Class RealEstateProperty
    Private nbr As String
    Private pType As String
    Private adrs As String
    Private ct As String
    Private stt As String
    Private zip As String
    Private levels As Byte
    Private yr As Integer
    Private beds As Byte
    Private baths As Single
    Private cond As String
    Private status As String
    Private cost As Double
    Private pFile As String
    Public Property PropertyNumber As String

        Get
            Return nbr
        End Get
        Set(ByVal value As String)
            nbr = value
        End Set
    End Property

    Public Property PropertyType As String
        Get
            Return pType
        End Get
        Set(ByVal value As String)
            pType = value
        End Set
    End Property

    Public Property Address As String
        Get
            Return adrs
        End Get
        Set(ByVal value As String)
            adrs = value
        End Set
    End Property

    Public Property City As String
        Get
            Return ct
        End Get
        Set(ByVal value As String)
            ct = value
        End Set
    End Property

    Public Property State As String
        Get
            Return stt
        End Get
        Set(ByVal value As String)
            stt = value
        End Set
    End Property

    Public Property ZIPCode As String
        Get
            Return zip
        End Get
        Set(ByVal value As String)
            zip = value
        End Set
    End Property

    Public Property Stories As Byte
        Get
            Stories = levels
        End Get
        Set(ByVal value As Byte)
            levels = value
        End Set
    End Property

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

    Public Property Bedrooms As Byte
        Get
            Bedrooms = beds
        End Get
        Set(ByVal value As Byte)
            beds = value
        End Set
    End Property

    Public Property Bathrooms As Single
        Get
            Bathrooms = baths
        End Get
        Set(ByVal value As Single)
            baths = value
        End Set
    End Property

    Public Property Condition As String
        Get
            Condition = cond
        End Get
        Set(ByVal value As String)
            cond = value
        End Set
    End Property

    Public Property SaleStatus As String
        Get
            SaleStatus = status
        End Get
        Set(ByVal value As String)
            status = value
        End Set
    End Property
    Public Property MarketValue As Double
        Get
            MarketValue = cost
        End Get
        Set(ByVal value As Double)
            cost = value
        End Set
    End Property

    Public Property PictureFile As String
        Get
            PictureFile = pFile
        End Get
        Set(ByVal value As String)
            pFile = value
        End Set
    End Property

    ' To determine that two properties are the same,
    ' we will test only the property number.
    ' We assume that if two properties have the same number,
    ' then it is the same property
    Public Overrides Function Equals(ByVal obj As Object) As Boolean
        Dim rep As RealEstateProperty = CType(obj, RealEstateProperty)

        If rep.PropertyNumber = PropertyNumber Then
            Equals = True
        Else
            Equals = False
        End If
    End Function
End Class

In the Solution Explorer, right-click Form1.vb and click Rename
Type AltairRealtors.vb and press Enter twice to display the form
From the Toolbox, add a list view to the form
Right-click that list box on the click Edit Columns...

Create the columns as follows:

(Name)	Text	TextAlign	Width
colPropertyNumber	Property #		65
colCity	City		75
colStories	Stories	Right	45
colYearBuilt	Year	Right	40
colBedrooms	Beds	Right	38
colBathrooms	Baths	Right	40
colCondition	Condition		80
colSaleStatus	Status		70
colMarketValue	Value	Right	75

Click OK

Design the form as follows:

Control	(Name)	Anchor	BorderStyle	SizeMode	Text
ListView	lvwProperties	Top, Bottom, Left, Right
Button	btnNewProperty	Bottom, Left			New Real Estate Property...
PictureBox	pbxPicture	Bottom, Right	FixedSingle	Zoom
Button	btnClose	Bottom, Right			Close

Form

Text:

Altair Realtors - Properties Listing

StartPosition:

CenterScreen

Right-click the form and click Edit Groups...
Create the groups as follows:

Header Name

Condominium lvgCondominium

Townhouse lvgTownhouse

Single Family lvgSingleFamily
Click OK
To create a new form, on the main menu, click Projects -> Add Windows Form...
Set the Name to PropertyEditor
Click Add
In the Dialogs section of the Toolbox, click OpenFileDialog
Click the form
In the Properties window, change its characteristics as follows:
(Name):      dlgPicture
DefaultExt: jpg
Filter:         JPEG Files (*.jpg,*.jpeg)|*.jpg
Title:          Select House Picture

Design the form as follows:

Control	(Name)	DropDownStyle	Text	Items	Modifiers	Other Properties
Label			Property Type:
ComboBox	cbxPropertyTypes	DropDownList		Condominium Townhouse Single Family Unknown	Public
Label			Property #:
TextBox	txtPropertyNumber				Public
Label			Address:
TextBox	txtAddress				Public
Label			City:
TextBox	txtCity				Public
Label			State:
ComboBox	cbxStates	DropDownList		AL, AK, AZ, AR, CA, CO, CT, DE, DC, FL, GA, HI, ID, IL, IN, IA, KS, KY, LA, ME, MD, MA, MI, MN, MS, MO, MT, NE, NV, NH, NJ, NM, NY, NC, ND, OH, OK, OR, PA, RI, SC, SD, TN, TX, UT, VT, VA, WA, WV, WI, WY	Public
Label			ZIP Code:
TextBox	txtZIPCode				Public
Label			Stories:
TextBox	txtStories				Public
Label			Year Built:
TextBox	txtYearBuilt				Public
Label			Condition:
ComboBox	cbxConditions	DropDownList		Excellent Good Shape Needs Fixing	Public
Label			Bedrooms:
TextBox	txtBedrooms		0		Public
Label			Bathrooms:
TextBox	txtBathrooms		0.00		Public
Label			Market Value:
TextBox	txtMarketValue		0.00		Public
Label			Sale Status:
ComboBox	cbxSaleStatus	DropDownList		Unspecified Available Sold	Public
Button	btnPicture		Picture...
PictureBox	pbxProperty					BorderStyle: FixedSingle SizeMode: Zoom
Button	btnOK		OK			DialogResult: OK
Button	btnCancel		Cancel			DialogResult: Cancel

Form

FormBorderStyle:

FixedDialog

Text:

Altair Realtors - Property Editor

StartPosition:

CenterScreen

AcceptButton:

btnOK

CancelButton:

btnCancel

MaximizeBox:

False

MinimizeBox:

False

ShowInTaskBar:

False

Right-click the form and click View Code

Declare two variables as follows:

Public Class PropertyEditor
    Public PictureChanged As Boolean
    Public PictureFile As String
End Class

In the top left combo box, select (PropertyEditor Events)
In the right combo box, selec Load

Implement the event as follows:

Public Class PropertyEditor
    Public PictureChanged As Boolean
    Public PictureFile As String

    Private Sub PropertyEditor_Load(ByVal sender As Object,
                                    ByVal e As System.EventArgs) Handles Me.Load
        PictureChanged = False
        PictureFile = "C:\Altair Realtors1\000-000.jpg"
    End Sub
End Class

In the top left combo box, select btnPicture
In the right combo box, select Click

Implement the event as follows:

Public Class PropertyEditor
    Public PictureChanged As Boolean
    Public PictureFile As String

    Private Sub PropertyEditor_Load(ByVal sender As Object,
                                    ByVal e As System.EventArgs) Handles Me.Load
        PictureChanged = False
        PictureFile = "C:\Altair Realtors1\000-000.jpg"
    End Sub

    Private Sub btnPicture_Click(ByVal sender As Object,
                                 ByVal e As System.EventArgs) Handles btnPicture.Click
        If dlgPicture.ShowDialog() = DialogResult.OK Then
            pbxProperty.Image = Image.FromFile(dlgPicture.FileName)
            PictureFile = dlgPicture.FileName
            PictureChanged = True
        End If
    End Sub
End Class

Practical Learning: Starting a Linked List Class

Click the AltairRealtors.vb [Design] tab
Right-click the form and click View Code

Change the file as follows:

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

Public Class AltairRealtors
    Private Properties As LinkedList(Of RealEstateProperty)

    Private Sub ShowProperties()
        ' Get a reference to the file that holds the records of properties
        Dim Filename As String = "C:\Altair Realtors\properties.atr"

        ' Make sure the file exists
        If File.Exists(Filename) = True Then
            ' if so, create a file stream
            Dim stmProperties As FileStream = New FileStream(Filename,
                                                      FileMode.Open,
                                                      FileAccess.Read)
            ' Create a binary formatter
            Dim bfmProperty As BinaryFormatter = New BinaryFormatter
            ' If some properties were created already,
            ' get them and store them in the collection
            Properties = CType(bfmProperty.Deserialize(stmProperties), LinkedList(Of RealEstateProperty))

            ' First, empty the list view
            lvwProperties.Items.Clear()
            Dim lviProperty As ListViewItem = Nothing

            ' Visit each property in the collection and add it to the list view
            For Each House As RealEstateProperty In Properties
                If house.PropertyType.Equals("Condominium") Then
                    lviProperty = New ListViewItem(House.PropertyNumber, lvwProperties.Groups(0))
                ElseIf House.PropertyType = "Townhouse" Then
                    lviProperty = New ListViewItem(House.PropertyNumber, lvwProperties.Groups(1))
                Else ' If house.PropertyType.Equals("Single Family"))
                    lviProperty = New ListViewItem(House.PropertyNumber, lvwProperties.Groups(2))

                    lviProperty.SubItems.Add(house.City)
                    lviProperty.SubItems.Add(CStr(house.Stories))
                    lviProperty.SubItems.Add(CStr(house.YearBuilt))
                    lviProperty.SubItems.Add(CStr(house.Bedrooms))
                    lviProperty.SubItems.Add(FormatNumber(House.Bathrooms))
                    lviProperty.SubItems.Add(house.Condition)
                    lviProperty.SubItems.Add(house.SaleStatus)
                    lviProperty.SubItems.Add(CStr(House.MarketValue))
                    lvwProperties.Items.Add(lviProperty)
                End If
            Next

            ' Close the file stream
            stmProperties.Close()
        End If
    End Sub

End Class

In the Names combo box, select AltairRealtors events
In the Procedures combo box, select Load

Implement the event as follows:

Private Sub AltairRealtors_Load(ByVal sender As Object,
                                    ByVal e As System.EventArgs) Handles Me.Load
        Properties = New LinkedList(Of RealEstateProperty)
        ShowProperties()
End Sub

Practical Learning: Adding the First Node

In the left combo box of the Code Editor, selec btnNewProperty
In the right combo box, select Click

Implement the event as follows:

Private Sub btnNewProperty_Click(ByVal sender As Object,
                                     ByVal e As System.EventArgs) Handles btnNewProperty.Click
        Dim Editor As PropertyEditor = New PropertyEditor

        Dim RndNumber As Random = New Random(DateTime.Now.Millisecond)
        Dim Number1 As Integer = RndNumber.Next(100, 999)
        Dim Number2 As Integer = RndNumber.Next(100, 999)
        Dim propNumber As String = Number1 & "-" & Number2

        editor.txtPropertyNumber.Text = propNumber

        ' Check that the directory that contains the list of properties exists.
        ' If it doesn't exist, create it
        Dim DirInfo As DirectoryInfo = Directory.CreateDirectory("C:\\Altair Realtors1")
        ' Get a reference to the file that holds the properties
        Dim Filename As String = "C:\Altair Realtors1\properties.atr"

        ' First check if the file was previously created
        If File.Exists(Filename) = True Then
            ' If the list of properties exists already,
            ' get it and store it in a file stream
            Dim stmProperties As FileStream = New FileStream(Filename,
                                                      FileMode.Open,
                                                      FileAccess.Read)
            Dim bfmProperty As BinaryFormatter = New BinaryFormatter
            ' Store the list of properties in the collection
            Properties = CType(bfmProperty.Deserialize(stmProperties), LinkedList(Of RealEstateProperty))
            ' Close the file stream
            stmProperties.Close()
        End If

        If editor.ShowDialog() = DialogResult.OK Then
            Dim Prop As RealEstateProperty = New RealEstateProperty

            Prop.PropertyNumber = Editor.txtPropertyNumber.Text
            Prop.PropertyType = Editor.cbxPropertyTypes.Text
            Prop.Address = Editor.txtAddress.Text
            Prop.City = Editor.txtCity.Text
            Prop.State = Editor.cbxStates.Text
            Prop.ZIPCode = Editor.txtZIPCode.Text
            Prop.Stories = CByte(Editor.txtStories.Text)
            Prop.YearBuilt = CInt(Editor.txtYearBuilt.Text)
            Prop.Bedrooms = CByte(Editor.txtBedrooms.Text)
            Prop.Bathrooms = CSng(Editor.txtBathrooms.Text)
            Prop.Condition = Editor.cbxConditions.Text
            Prop.SaleStatus = Editor.cbxSaleStatus.Text
            Prop.MarketValue = CDbl(Editor.txtMarketValue.Text)
            If Editor.PictureFile <> "" Then
                Dim PictureFile As FileInfo = New FileInfo(Editor.PictureFile)
                PictureFile.CopyTo("C:\Altair Realtors1\" &
                              Editor.txtPropertyNumber.Text &
                              PictureFile.Extension)
                Prop.PictureFile = "C:\Altair Realtors1\" &
                                  Editor.txtPropertyNumber.Text &
                                  PictureFile.Extension
            Else
                Prop.PictureFile = "C:\Altair Realtors1\000-000.jpg"
            End If

            ' Add the property in the collection
            Properties.AddFirst(Prop)

            ' Get a reference to the properties file
            Dim strFilename As String = DirInfo.FullName & "\properties.atr"
            ' Create a file stream to hold the list of properties
            Dim stmProperties As FileStream = New FileStream(strFilename,
                                                      FileMode.Create,
                                                      FileAccess.Write)
            Dim bfmProperty As BinaryFormatter = New BinaryFormatter

            ' Serialize the list of properties
            bfmProperty.Serialize(stmProperties, Properties)
            ' Close the file stream
            stmProperties.Close()

            ' Show the list of properties
            ShowProperties()
End If
    End Sub

In the left combo box of the Code Editor, select lvwProperties
In the Events (right) combo box, select ItemSelectionChanged

Implement the event as follows:

Private Sub lvwProperties_ItemSelectionChanged(ByVal sender As Object,
                                                   ByVal e As System.Windows.Forms.ListViewItemSelectionChangedEventArgs) Handles lvwProperties.ItemSelectionChanged
        Dim CurrentProperty As RealEstateProperty = New RealEstateProperty

        For Each Prop As RealEstateProperty In Properties
            If Prop.PropertyNumber = e.Item.SubItems(0).Text Then
                pbxProperty.Image = Image.FromFile(Prop.PictureFile)
            End If
        Next
End Sub

To execute, press F5
Click the New Real Estate Property button and create a property
Click OK
Copy the following picture and paste (or save it) in the Altair Realtors folder on the C: drive (or the folder that contains the file properties of this project):
Create some properties
Close the form and return to your programming environment

Practical Learning: Checking a Node

In the Names combo box, select lvwProperties
In the Procedures combo box, select DoubleClick

Implement the event as follows:

Private Sub lvwProperties_DoubleClick(ByVal sender As Object,
              ByVal e As System.EventArgs) Handles lvwProperties.DoubleClick
        If (lvwProperties.SelectedItems.Count = 0) Or
           (lvwProperties.SelectedItems.Count > 1) Then
            Exit Sub
        End If

        ' Get a reference to the file that holds the properties
        Dim Filename As String = "C:\Altair Realtors\properties.atr"

        ' Open the file that contains the properties
        Dim stmProperties As FileStream = New FileStream(Filename,
                                                  FileMode.Open,
                                                  FileAccess.Read)
        Dim bfmProperty As BinaryFormatter = New BinaryFormatter
        ' Store the list of properties in the collection
        Properties = bfmProperty.Deserialize(stmProperties)
        ' Close the file stream
        stmProperties.Close()

        ' Get the property that the user double-clicked
        Dim lviProperty As ListViewItem = lvwProperties.SelectedItems(0)
        Dim House As RealEstateProperty = New RealEstateProperty
        For Each Prop As RealEstateProperty In Properties
            If Prop.PropertyNumber = lviProperty.Text Then
                House = Prop
            End If
        Next

        ' Get a reference to the property editor
        Dim Editor As PropertyEditor = New PropertyEditor

        ' Prepare to fill the editor with the
        ' values of the property the user double-clicked
        Editor.txtPropertyNumber.Text = House.PropertyNumber
        Editor.cbxPropertyTypes.Text = House.PropertyType
        Editor.txtAddress.Text = House.Address
        Editor.txtCity.Text = House.City
        Editor.cbxStates.Text = House.State
        Editor.txtZIPCode.Text = House.ZIPCode
        editor.txtStories.Text = CStr(house.Stories)
        editor.txtYearBuilt.Text = CStr(house.YearBuilt)
        editor.txtBedrooms.Text = CStr(house.Bedrooms)
        editor.txtBathrooms.Text = FormatNumber(house.Bathrooms)
        editor.cbxConditions.Text = house.Condition
        editor.cbxSaleStatus.Text = house.SaleStatus
        editor.txtMarketValue.Text = FormatNumber(house.MarketValue)
        editor.pbxProperty.Image = Image.FromFile(house.PictureFile)

        ' Disable the property number just in
        ' case the user tries to change it
        Editor.txtPropertyNumber.Enabled = False

        ' Show the property editor
        editor.ShowDialog()
End Sub

Press F5 to execute the application
Double-click one of the properties
Close the forms and return to your programming environment

Practical Learning: Updating a Node

Change the DoubleClick event as follows:

Private Sub lvwProperties_DoubleClick(ByVal sender As Object,
               ByVal e As System.EventArgs) Handles lvwProperties.DoubleClick
        If (lvwProperties.SelectedItems.Count = 0) Or
           (lvwProperties.SelectedItems.Count > 1) Then
            Exit Sub
        End If

        ' Get a reference to the file that holds the properties
        Dim Filename As String = "C:\Altair Realtors\properties.atr"

        ' Open the file that contains the properties
        Dim stmProperties As FileStream = New FileStream(Filename,
                                                  FileMode.Open,
                                                  FileAccess.Read)
        Dim bfmProperty As BinaryFormatter = New BinaryFormatter
        ' Store the list of properties in the linked list
        Properties = bfmProperty.Deserialize(stmProperties)
        ' Close the file stream
        stmProperties.Close()

        ' Get the property that the user double-clicked
        Dim lviProperty = lvwProperties.SelectedItems(0)
        Dim House As RealEstateProperty = New RealEstateProperty
        ' Get the property number the user double-clicked
        House.PropertyNumber = lviProperty.Text

        ' Find the property in the list
        Dim NodeProperty As LinkedListNode(Of RealEstateProperty) = Properties.Find(House)

        ' Get a reference to the property editor
        Dim Editor As PropertyEditor = New PropertyEditor

        ' Prepare to fill the editor with the values of the property the user double-clicked
        Editor.txtPropertyNumber.Text = NodeProperty.Value.PropertyNumber
        Editor.cbxPropertyTypes.Text = NodeProperty.Value.PropertyType
        Editor.txtAddress.Text = NodeProperty.Value.Address
        Editor.txtCity.Text = NodeProperty.Value.City
        Editor.cbxStates.Text = NodeProperty.Value.State
        Editor.txtZIPCode.Text = NodeProperty.Value.ZIPCode
        Editor.txtStories.Text = CStr(NodeProperty.Value.Stories)
        Editor.txtYearBuilt.Text = CStr(NodeProperty.Value.YearBuilt)
        Editor.txtBedrooms.Text = CStr(NodeProperty.Value.Bedrooms)
        Editor.txtBathrooms.Text = FormatNumber(NodeProperty.Value.Bathrooms)
        Editor.cbxConditions.Text = NodeProperty.Value.Condition
        Editor.cbxSaleStatus.Text = NodeProperty.Value.SaleStatus
        Editor.txtMarketValue.Text = FormatNumber(NodeProperty.Value.MarketValue)
        Editor.pbxProperty.Image = Image.FromFile(NodeProperty.Value.PictureFile)
        Editor.PictureFile = NodeProperty.Value.PictureFile

        ' Disable the property number so the user cannot change it
        Editor.txtPropertyNumber.Enabled = False

        ' Show the property editor
        If Editor.ShowDialog() = System.Windows.Forms.DialogResult.OK Then
            ' For each value that has changed in the property, update its node
            NodeProperty.Value.PropertyType = Editor.cbxPropertyTypes.Text
            NodeProperty.Value.Address = Editor.txtAddress.Text
            NodeProperty.Value.City = Editor.txtCity.Text
            NodeProperty.Value.State = Editor.cbxStates.Text
            NodeProperty.Value.ZIPCode = Editor.txtZIPCode.Text
            NodeProperty.Value.Stories = CByte(Editor.txtStories.Text)
            NodeProperty.Value.YearBuilt = CInt(Editor.txtYearBuilt.Text)
            NodeProperty.Value.Bedrooms = CByte(Editor.txtBedrooms.Text)
            NodeProperty.Value.Bathrooms = CSng(Editor.txtBathrooms.Text)
            NodeProperty.Value.Condition = Editor.cbxConditions.Text
            NodeProperty.Value.SaleStatus = Editor.cbxSaleStatus.Text
            NodeProperty.Value.MarketValue = CDbl(Editor.txtMarketValue.Text)
            NodeProperty.Value.PictureFile = Editor.PictureFile

            ' Start saving the linked list
            stmProperties = New FileStream(Filename,
                                           FileMode.OpenOrCreate,
                                           FileAccess.ReadWrite)
            bfmProperty = New BinaryFormatter

            ' Serialize the list of properties
            bfmProperty.Serialize(stmProperties, Properties)
            ' Close the file stream
            stmProperties.Close()

            ' Show the list of properties
            ShowProperties()
        End If
    End Sub

Press F5 to execute
Double-click the row in the Townhouse section
Change its year built to 2005
Change its market value to 585985 (If possible, also change its picture)
Click OK
Close the form and return to your programming environment

Practical Learning: Navigating Among Nodes

To create a new form, on the main menu, click Projects -> Add Windows Form...
Set the Name to PropertiesReview
Click Add

Design the form as follows:

Control	(Name)	DropDownStyle	Text	Other Properties
Label			Property #:
TextBox	txtPropertyNumber
Label			Property Type:
TextBox	txtPropertyType
Label			Address:
TextBox	txtAddress
Label			City:
TextBox	txtCity
Label			State:
TexBox	txtState
Label			ZIP Code:
TextBox	txtZIPCode
Label			Stories:
TextBox	txtStories
Label			Year Built:
TextBox	txtYearBuilt
Label			Condition:
TextBox	txtCondition
Label			Bedrooms:
TextBox	txtBedrooms		0
Label			Bathrooms:
TextBox	txtBathrooms		0.00
Label			Market Value:
TextBox	txtMarketValue		0.00
Label			Sale Status:
TextBox	txtStatus
PictureBox	pbxProperty			BorderStyle: FixedSingle SizeMode: Zoom
Button	btnClose		Close
Button	btnFirst		First
Label	lblRecordNumber		000 of 000
Button	btnPrevious		Previous
Button	btnLast		Last

Right-click the form and click View Code

Change the file as follows:

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

Public Class PropertiesReview
    Private Index As Integer
    Private Properties As LinkedList(Of RealEstateProperty)
    Dim CurrentNode As LinkedListNode(Of RealEstateProperty)
End Class

In the Names combo box, select (PropertiesReview Events)
In the Procedures combo box, select Load

Implement the event as follows:

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

Public Class PropertiesReview
    Private Index As Integer
    Private Properties As LinkedList(Of RealEstateProperty)
    Dim CurrentNode As LinkedListNode(Of RealEstateProperty)

    Private Sub PropertiesReview_Load(ByVal sender As Object,
                                      ByVal e As System.EventArgs) Handles Me.Load
        Index = 1
        ' Get a reference to the file that holds the records of properties
        Dim Filename As String = "C:\Altair Realtors\properties.atr"

        ' Make sure the file exists
        If File.Exists(Filename) = True Then
            ' if so, create a file stream
            Dim stmProperties As FileStream = New FileStream(Filename,
                                                      FileMode.Open,
                                                      FileAccess.Read)
            ' Create a binary formatter
            Dim bfmProperty As BinaryFormatter = New BinaryFormatter
            ' If some properties were created already,
            ' get them and store them in the collection
            Properties = bfmProperty.Deserialize(stmProperties)
        End If
    End Sub
End Class

In the Names combo box, select btnFirst
In the Procedures combo box, select Click

Implement the event as follows:

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

Public Class PropertiesReview
    Private Index As Integer
    Private Properties As LinkedList(Of RealEstateProperty)
    Dim CurrentNode As LinkedListNode(Of RealEstateProperty)

    Private Sub PropertiesReview_Load(ByVal sender As Object,
                                      ByVal e As System.EventArgs) Handles Me.Load
        Index = 1
        ' Get a reference to the file that holds the records of properties
        Dim Filename As String = "C:\Altair Realtors\properties.atr"

        ' Make sure the file exists
        If File.Exists(Filename) = True Then
            ' if so, create a file stream
            Dim stmProperties As FileStream = New FileStream(Filename,
                                                      FileMode.Open,
                                                      FileAccess.Read)
            ' Create a binary formatter
            Dim bfmProperty As BinaryFormatter = New BinaryFormatter
            ' If some properties were created already,
            ' get them and store them in the collection
            Properties = bfmProperty.Deserialize(stmProperties)
        End If

        btnFirst_Click(sender, e)
    End Sub

    Private Sub btnFirst_Click(ByVal sender As Object,
                               ByVal e As System.EventArgs) Handles btnFirst.Click
        Index = 1
        CurrentNode = Properties.First

        txtPropertyNumber.Text = CurrentNode.Value.PropertyNumber
        txtPropertyType.Text = CurrentNode.Value.PropertyType
        txtAddress.Text = CurrentNode.Value.Address
        txtCity.Text = CurrentNode.Value.City
        txtState.Text = CurrentNode.Value.State
        txtZIPCode.Text = CurrentNode.Value.ZIPCode
        txtStories.Text = CStr(CurrentNode.Value.Stories)
        txtYearBuilt.Text = CStr(CurrentNode.Value.YearBuilt)
        txtBedrooms.Text = CStr(CurrentNode.Value.Bedrooms)
        txtBathrooms.Text = FormatNumber(CurrentNode.Value.Bathrooms)
        txtCondition.Text = CurrentNode.Value.Condition
        txtSaleStatus.Text = CurrentNode.Value.SaleStatus
        txtMarketValue.Text = FormatNumber(CurrentNode.Value.MarketValue)
        pbxProperty.Image = Image.FromFile(CurrentNode.Value.PictureFile)

        lblRecordNumber.Text = "1 of " & CStr(Properties.Count)
    End Sub
End Class

In the Names combo box, select btnPrevious
In the Procedures combo box, select Click

Implement the event as follows:

Private Sub btnPrevious_Click(ByVal sender As Object,
                   ByVal e As System.EventArgs) Handles btnPrevious.Click
        Index = Index - 1

        If Index <= 1 Then
            btnFirst_Click(sender, e)
        Else
            Dim Current As LinkedListNode(Of RealEstateProperty) = CurrentNode.Previous

            txtPropertyNumber.Text = Current.Value.PropertyNumber
            txtPropertyType.Text = Current.Value.PropertyType
            txtAddress.Text = Current.Value.Address
            txtCity.Text = Current.Value.City
            txtState.Text = Current.Value.State
            txtZIPCode.Text = Current.Value.ZIPCode
            txtStories.Text = CStr(Current.Value.Stories)
            txtYearBuilt.Text = CStr(Current.Value.YearBuilt)
            txtBedrooms.Text = CStr(Current.Value.Bedrooms)
            txtBathrooms.Text = FormatNumber(Current.Value.Bathrooms)
            txtCondition.Text = Current.Value.Condition
            txtSaleStatus.Text = Current.Value.SaleStatus
            txtMarketValue.Text = FormatNumber(Current.Value.MarketValue)

            lblRecordNumber.Text = Index & " of " & CStr(Properties.Count)
        End If
End Sub

In the Names combo box, select btnNext
In the Procedures combo box, select Click
In the Names combo box, select btnLast
In the Procedures combo box, select Click

Implement the events as follows:

Private Sub btnNext_Click(ByVal sender As Object,
                          ByVal e As System.EventArgs) Handles btnNext.Click
        Index = Index + 1

        If Index >= Properties.Count Then
            btnLast_Click(sender, e)
        Else
            Dim Current As LinkedListNode(Of RealEstateProperty) = CurrentNode.Next

            txtPropertyNumber.Text = Current.Value.PropertyNumber
            txtPropertyType.Text = Current.Value.PropertyType
            txtAddress.Text = Current.Value.Address
            txtCity.Text = Current.Value.City
            txtState.Text = Current.Value.State
            txtZIPCode.Text = Current.Value.ZIPCode
            txtStories.Text = CStr(Current.Value.Stories)
            txtYearBuilt.Text = CStr(Current.Value.YearBuilt)
            txtBedrooms.Text = CStr(Current.Value.Bedrooms)
            txtBathrooms.Text = FormatNumber(Current.Value.Bathrooms)
            txtCondition.Text = Current.Value.Condition
            txtSaleStatus.Text = Current.Value.SaleStatus
            txtMarketValue.Text = FormatNumber(Current.Value.MarketValue)
            pbxProperty.Image = Image.FromFile(Current.Value.PictureFile)

            lblRecordNumber.Text = CStr(Index) & " of " & CStr(Properties.Count)
        End If
End Sub

Private Sub btnLast_Click(ByVal sender As Object,
                          ByVal e As System.EventArgs) Handles btnLast.Click
        Index = Properties.Count
        CurrentNode = Properties.Last

        txtPropertyNumber.Text = CurrentNode.Value.PropertyNumber
        txtPropertyType.Text = CurrentNode.Value.PropertyType
        txtAddress.Text = CurrentNode.Value.Address
        txtCity.Text = CurrentNode.Value.City
        txtState.Text = CurrentNode.Value.State
        txtZIPCode.Text = CurrentNode.Value.ZIPCode
        txtStories.Text = CStr(CurrentNode.Value.Stories)
        txtYearBuilt.Text = CStr(CurrentNode.Value.YearBuilt)
        txtBedrooms.Text = CStr(CurrentNode.Value.Bedrooms)
        txtBathrooms.Text = FormatNumber(CurrentNode.Value.Bathrooms)
        txtCondition.Text = CurrentNode.Value.Condition
        txtSaleStatus.Text = CurrentNode.Value.SaleStatus
        txtMarketValue.Text = FormatNumber(CurrentNode.Value.MarketValue)
        pbxProperty.Image = Image.FromFile(CurrentNode.Value.PictureFile)

        lblRecordNumber.Text = CStr(Properties.Count) & " of " & CStr(Properties.Count)
End Sub

In the Names combo box, select btnClose
In the Procedures combo box, select Click

Implement the event as follows:

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

Display the Properties Listing form
On the right side of the New Real Estate Property button, add a new button and set its characteristics as follows:
(Name): btnReviewProperties
Text: Review Properties...

Double-click the Navigate button and implement its event as follows:

Private Sub btnReviewProperties_Click(ByVal sender As Object,
                 ByVal e As System.EventArgs) Handles btnReviewProperties.Click
        Dim pr As PropertiesReview = New PropertiesReview

        pr.ShowDialog()
End Sub

Press F5 to execute
Click the Review Properties button
Close the forms and return to your programming environment

Practical Learning: Inserting Nodes

Display the Properties Listing form
In the Menus & Toolbars section of the Toolbox, click ContextMenuStrip and click the form

Click the menu items as follows:

(Name)	Enabled	Text
mnuNewProperty		New Property...
mnuEditProperty	False	Edit Property...
mnuInsertBefore	False	Insert Property...
mnuInsertAfter	False	Insert After

Under the form, click the context menu strip
In the Properties window, change its name to cmsProperties
On the form, click the list view
In the Properties window, set its ContextMenuStrip to cmsProperties
Right-click the form and click View Code
In the Names combo box, select mnuNewProperty
In the Procedures combo box, select Click

Implement the event as follows:

Private Sub mnuNewProperty_Click(ByVal sender As Object,
                    ByVal e As System.EventArgs) Handles mnuNewProperty.Click
        btnNewProperty_Click(sender, e)
End Sub

Locate the ItemSelectionChanged event and change its implementation as follows:

Private Sub lvwProperties_ItemSelectionChanged(ByVal sender As Object,
                                               ByVal e As System.Windows.Forms.ListViewItemSelectionChangedEventArgs) Handles lvwProperties.ItemSelectionChanged
        Dim CurrentProperty As RealEstateProperty = New RealEstateProperty

        For Each Prop As RealEstateProperty In Properties
            If Prop.PropertyNumber = e.Item.SubItems(0).Text Then
                pbxProperty.Image = Image.FromFile(Prop.PictureFile)
            End If
        Next

        If lvwProperties.SelectedItems.Count = 1 Then
            mnuInsertBefore.Enabled = True
            mnuEditProperty.Enabled = True
            mnuInsertAfter.Enabled = True
        Else
            mnuInsertBefore.Enabled = False
            mnuEditProperty.Enabled = False
            mnuInsertAfter.Enabled = False
        End If
End Sub

In the Names combo box, select mnuEditProperties
In the Procedures combo box, select Click

Implement the event as follows:

Private Sub mnuEditProperty_Click(ByVal sender As Object,
                                  ByVal e As System.EventArgs) Handles mnuEditProperty.Click
    lvwProperties_DoubleClick(sender, e)
End Sub

In the Names combo box, select mnuInsertBefore
In the Procedures combo box, select Click

Implement the event as follows:

Private Sub mnuInsertBefore_Click(ByVal sender As Object,
                                      ByVal e As System.EventArgs) Handles mnuInsertBefore.Click
        Dim Editor As PropertyEditor = New PropertyEditor
        Dim Filename As String = "C:\Altair Realtors1\properties.atr"
        Dim DirInfo As DirectoryInfo = Directory.CreateDirectory("C:\\Altair Realtors1")

        If File.Exists(Filename) = True Then
            Dim stmProperties As FileStream = New FileStream(Filename,
                                                      FileMode.Open,
                                                      FileAccess.Read)
            Dim bfmProperties As BinaryFormatter = New BinaryFormatter

            Properties = bfmProperties.Deserialize(stmProperties)
            stmProperties.Close()
            stmProperties.Close()
        End If

        Dim rep As RealEstateProperty = New RealEstateProperty
        Dim strPropertyNumber As String = lvwProperties.SelectedItems(0).Text
        rep.PropertyNumber = lvwProperties.SelectedItems(0).Text

        Dim RndNumber As Random = New Random(DateTime.Now.Millisecond)
        Dim Number1 As Integer = RndNumber.Next(100, 999)
        Dim Number2 As Integer = RndNumber.Next(100, 999)
        Dim PropNumber As String = Number1 + "-" & Number2

        Editor.txtPropertyNumber.Text = PropNumber
        Editor.cbxPropertyTypes.Text = lvwProperties.SelectedItems(0).Group.Header
        Editor.cbxPropertyTypes.Enabled = False

        Dim NodeProperty As LinkedListNode(Of RealEstateProperty) = Properties.Find(rep)

        If NodeProperty Is Nothing Then
            If editor.ShowDialog() = System.Windows.Forms.DialogResult.OK Then
                Dim Prop As RealEstateProperty = New RealEstateProperty

                Prop.PropertyNumber = Editor.txtPropertyNumber.Text
                Prop.PropertyType = Editor.cbxPropertyTypes.Text
                Prop.Address = Editor.txtAddress.Text
                Prop.City = Editor.txtCity.Text
                Prop.State = Editor.cbxStates.Text
                Prop.ZIPCode = Editor.txtZIPCode.Text
                Prop.Stories = CByte(Editor.txtStories.Text)
                Prop.YearBuilt = CInt(Editor.txtYearBuilt.Text)
                Prop.Bedrooms = CByte(Editor.txtBedrooms.Text)
                Prop.Bathrooms = CSng(Editor.txtBathrooms.Text)
                Prop.Condition = Editor.cbxConditions.Text
                Prop.SaleStatus = Editor.cbxSaleStatus.Text
                Prop.MarketValue = CDbl(Editor.txtMarketValue.Text)
                If Not Editor.PictureFile = "" Then
                    Dim PictureFile As FileInfo = New FileInfo(Editor.PictureFile)
                    PictureFile.CopyTo("C:\Altair Realtors1\" &
                                      Editor.txtPropertyNumber.Text &
                                      PictureFile.Extension)
                    Prop.PictureFile = "C:\Altair Realtors1\" &
                                      Editor.txtPropertyNumber.Text &
                                      PictureFile.Extension
                Else
                    Prop.PictureFile = "C:\Altair Realtors1\000-000.jpg"
                End If

                ' Insert the property before the currently selected node
                Properties.AddBefore(NodeProperty, Prop)

                ' Get a reference to the properties file
                Dim strFilename As String = DirInfo.FullName & "\properties.atr"
                ' Create a file stream to hold the list of properties
                Dim stmProperties As FileStream = New FileStream(strFilename,
                                                          FileMode.Create,
                                                          FileAccess.Write)
                Dim bfmProperty As BinaryFormatter = New BinaryFormatter

                ' Serialize the list of properties
                bfmProperty.Serialize(stmProperties, Properties)
                ' Close the file stream
                stmProperties.Close()

                ' Show the list of properties
                ShowProperties()
            End If
        End If
End Sub

In the Names combo box, select mnuInsertAfter
In the Procedures combo box, select Click

Implement the event as follows:

Private Sub mnuInsertAfter_Click(ByVal sender As Object,
                                     ByVal e As System.EventArgs) Handles mnuInsertAfter.Click
        Dim Editor As PropertyEditor = New PropertyEditor
        Dim Filename As String = "C:\Altair Realtors1\properties.atr"
        Dim DirInfo As DirectoryInfo = Directory.CreateDirectory("C:\\Altair Realtors1")

        If File.Exists(Filename) = True Then
            Dim stmProperties As FileStream = New FileStream(Filename,
                                                      FileMode.Open,
                                                      FileAccess.Read)
            Dim bfmProperties As BinaryFormatter = New BinaryFormatter

            Properties = bfmProperties.Deserialize(stmProperties)
            ' Close the file stream
            stmProperties.Close()
            stmProperties.Close()
        End If

        Dim rep As RealEstateProperty = New RealEstateProperty
        Dim strPropertyNumber As String = lvwProperties.SelectedItems(0).Text
        rep.PropertyNumber = lvwProperties.SelectedItems(0).Text

        Dim RndNumber As Random = New Random(DateTime.Now.Millisecond)
        Dim Number1 As Integer = RndNumber.Next(100, 999)
        Dim Number2 As Integer = RndNumber.Next(100, 999)
        Dim PropNumber As String = Number1 & "-" & Number2

        Editor.txtPropertyNumber.Text = PropNumber
        Editor.cbxPropertyTypes.Text = lvwProperties.SelectedItems(0).Group.Header
        Editor.cbxPropertyTypes.Enabled = False

        Dim NodeProperty As LinkedListNode(Of RealEstateProperty) = Properties.Find(rep)

        If NodeProperty Is Nothing Then
            If Editor.ShowDialog() = System.Windows.Forms.DialogResult.OK Then
                Dim Prop As RealEstateProperty = New RealEstateProperty

                Prop.PropertyNumber = Editor.txtPropertyNumber.Text
                Prop.PropertyType = Editor.cbxPropertyTypes.Text
                Prop.Address = Editor.txtAddress.Text
                Prop.City = Editor.txtCity.Text
                Prop.State = Editor.cbxStates.Text
                Prop.ZIPCode = Editor.txtZIPCode.Text
                Prop.Stories = CByte(Editor.txtStories.Text)
                Prop.YearBuilt = CInt(Editor.txtYearBuilt.Text)
                Prop.Bedrooms = CByte(Editor.txtBedrooms.Text)
                Prop.Bathrooms = CSng(Editor.txtBathrooms.Text)
                Prop.Condition = Editor.cbxConditions.Text
                Prop.SaleStatus = Editor.cbxSaleStatus.Text
                Prop.MarketValue = CDbl(Editor.txtMarketValue.Text)
                If Not Editor.PictureFile = "" Then
                    Dim PictureFile As FileInfo = New FileInfo(Editor.PictureFile)
                    PictureFile.CopyTo("C:\Altair Realtors1\" &
                                      Editor.txtPropertyNumber.Text &
                                      PictureFile.Extension)
                    Prop.PictureFile = "C:\Altair Realtors1\" &
                                  Editor.txtPropertyNumber.Text &
                                  PictureFile.Extension
                Else
                    Prop.PictureFile = "C:\Altair Realtors1\000-000.jpg"
                End If

                ' Insert the property before the currently selected node
                Properties.AddAfter(NodeProperty, Prop)

                ' Get a reference to the properties file
                Dim strFilename As String = DirInfo.FullName & "\properties.atr"
                ' Create a file stream to hold the list of properties
                Dim stmProperties As FileStream = New FileStream(strFilename,
                                                          FileMode.Create,
                                                          FileAccess.Write)
                Dim bfmProperty As BinaryFormatter = New BinaryFormatter

                ' Serialize the list of properties
                bfmProperty.Serialize(stmProperties, Properties)
                ' Close the file stream
                stmProperties.Close()

                ' Show the list of properties
                ShowProperties()
            End If
        End If
End Sub

To execute, press F5
Create some properties (let the application generate the property number) (the new records are in bold):
Close the form and return to your programming environment

Practical Learning: Deleting a Node

Display the Properties Listing form
Under the form, click cmsProperties

Add a new menu item as follows:

(Name)	Enabled	Text
mnuNewProperty		New Property...
mnuEditProperty	False	Edit Property...
mnuInsertBefore	False	Insert Property...
mnuInsertAfter	False	Insert After
mnuDeleteProperty	False	Delete Property

Right-click the form and click View Code

In the file, locate the ItemSelectionChanged event and change its implementation as follows:

Private Sub lvwProperties_ItemSelectionChanged(ByVal sender As Object,
          ByVal e As System.Windows.Forms.ListViewItemSelectionChangedEventArgs) Handles lvwProperties.ItemSelectionChanged
        Dim CurrentProperty As RealEstateProperty = New RealEstateProperty

        For Each Prop As RealEstateProperty In Properties
            If Prop.PropertyNumber = e.Item.SubItems(0).Text Then
                pbxProperty.Image = Image.FromFile(Prop.PictureFile)
            End If
        Next

        If lvwProperties.SelectedItems.Count = 1 Then
            mnuInsertBefore.Enabled = True
            mnuEditProperty.Enabled = True
            mnuInsertAfter.Enabled = True
            mnuDeleteProperty.Enabled = True
        Else
            mnuInsertBefore.Enabled = False
            mnuEditProperty.Enabled = False
            mnuInsertAfter.Enabled = False
            mnuDeleteProperty.Enabled = False
        End If
    End Sub

In the Names combo box, select mnuDeleteProperty
In the Procedures combo box, select Click

Implement the event as follows:

Private Sub mnuDeleteProperty_Click(ByVal sender As Object,
                 ByVal e As System.EventArgs) Handles mnuDeleteProperty.Click
        Dim Editor As PropertyEditor = New PropertyEditor
        Dim Filename As String = "C:\Altair Realtors\properties.atr"
        Dim DirInfo As DirectoryInfo = 
        	Directory.CreateDirectory("C:\Altair Realtors")

        ' Open the file that holds the properties
        If File.Exists(Filename) = True Then
            Dim stmProperties As FileStream = New FileStream(Filename,
                                                      FileMode.Open,
                                                      FileAccess.Read)
            Dim bfmProperties As BinaryFormatter = New BinaryFormatter

            Properties = bfmProperties.Deserialize(stmProperties)
            stmProperties.Close()
            stmProperties.Close()
        End If

        ' Create a real estate property using the property number that the user double-clicked
        Dim rep As RealEstateProperty = New RealEstateProperty
        Dim strPropertyNumber As String = lvwProperties.SelectedItems(0).Text
        rep.PropertyNumber = lvwProperties.SelectedItems(0).Text

        ' Ask the compiler to locate that property
        Dim NodeProperty As LinkedListNode(Of RealEstateProperty) = 
        						Properties.Find(rep)

        ' Just in case, make sure the property was found
        If Not NodeProperty Is Nothing Then
            ' Present a warning message to the user
            If MsgBox("Are you sure you want to delete this property?",
                      MsgBoxStyle.YesNo,
                                "Altair Realtors") = MsgBoxResult.Yes Then
                ' If the user clicks yes, delete the property
                Properties.Remove(NodeProperty)

                ' Save the list of properties
                Dim strFilename As String = DirInfo.FullName + "\properties.atr"
                Dim stmProperties As FileStream = New FileStream(strFilename,
                                                          FileMode.Create,
                                                          FileAccess.Write)
                Dim bfmProperty As BinaryFormatter = New BinaryFormatter

                bfmProperty.Serialize(stmProperties, Properties)
                stmProperties.Close()

                ' Show the new list of properties
                ShowProperties()
            End If
        End If
End Sub

In the Names combo box, select btnClose
In the Procedures combo box, select Click

Implement the event as follows:

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

To execute, press F5
Right-click one of the records and click Delete Property
Click No
Right-click another row and click Delete Property
Click Yes
Close the form and return to your programming environment