Adding To Array Error: Must Cast A New Object

Question

Hello,

I am currently having a bit of trouble trying to add a new object to an array of "Apps", the array being AppDirectory. In the below code, what I am doing is reading a file called "directory.txt"... It will read and create an array of Apps with the name, description and location of the executable, when the error occurs, it is asking me to create a new instance of the variable, even though it is already cast as a new App before the loop begins.

Here is the code:

Imports System.Reflection
Imports System.Drawing

Public Class App

    ''' <summary>
    ''' Add your application to the ColourSoft app directory.
    ''' </summary>
    ''' <param name="appTitle">The title of your application.</param>
    ''' <param name="appDescription">A description of what your application does.</param>
    ''' <param name="appLocation">The executable name of the application.</param>
    ''' <param name="appIcon">The icon of the application.</param>
    ''' <remarks></remarks>
    Public Shared Sub Add(ByVal appTitle As String, ByVal appDescription As String, ByVal appLocation As String, ByVal appIcon As Image)
        Dim _app As App = New App()
        AppCollection.Add(_app)
        Dim i As Integer = AppCollection.IndexOf(_app)
        AppCollection(i).Title = appTitle
        AppCollection(i).Description = appDescription
        AppCollection(i).AppForm = appLocation
        AppCollection(i).AppIcon = appIcon

    End Sub

    Public Shared Property AppCollection() As AppDirectory

    Public Shared Sub GetApps()
        Dim _CustApp As CustomApp = New CustomApp()
        For Each _app As App In AppCollection
            _CustApp.IsActive = False
            _CustApp.Title = _app.Title
            _CustApp.Description = _app.Description
            _CustApp.AssociatedForm = _app.AppForm
            _CustApp.Dock = DockStyle.Left
            _CustApp.Width = 110
            MainForm.pnlApplications.Controls.Add(_CustApp)
        Next
    End Sub

    Public Class AppDirectory
        Inherits Generic.List(Of App)

    End Class

    Declare Function ExtractIcon Lib "shell32.dll" Alias "ExtractIconExA" (ByVal lpszFile As String, ByVal nIconIndex As Integer, ByRef phiconLarge As Integer, ByRef phiconSmall As Integer, ByVal nIcons As Integer) As Integer

    'All private methods and variables
    Private _appTitle As String
    Private _appDescription As String
    Private _appForm As String
    Private _appIcon As Image

    Public Property Title() As String
        Get
            Return _appTitle
        End Get
        Set(ByVal value As String)
            _appTitle = value
        End Set
    End Property

    Public Property Description() As String
        Get
            Return _appDescription
        End Get
        Set(ByVal value As String)
            _appDescription = value
        End Set
    End Property

    Public Property AppForm() As String
        Get
            Return _appForm
        End Get
        Set(ByVal value As String)
            _appForm = value
        End Set
    End Property

    Public Property AppIcon() As Image
        Get
            Return _appIcon
        End Get
        Set(ByVal value As Image)
            _appIcon = value
        End Set
    End Property

    Public Shared Sub GetAppDirectoryFile()
        Dim file As String = My.Computer.FileSystem.ReadAllText("directory.txt")
        Dim contents() As String = file.Split(vbCrLf)
        Dim _title As String = ""
        Dim _description As String = ""
        Dim _appform As String = ""
        Dim _appicon As Image = Nothing
        For Each statement As String In contents
            Select Case statement
                Case GetFromContains(statement, "name")
                    _title = ReadLine(statement, "=", 1)
                Case GetFromContains(statement, "description")
                    _description = ReadLine(statement, "=", 1)
                Case GetFromContains(statement, "location")
                    _appform = ReadLine(statement, "=", 1)
                    '_appicon = ReturnIcon(_app.AppForm, 0, True).ToBitmap
                Case GetFromContains(statement, "end")
                    Add(_title, _description, _appform, _appicon)
            End Select
        Next
    End Sub

    Public Shared Function GetFromContains(ByVal value As String, ByVal valueToFind As String) As String
        If value.Contains(valueToFind) = True Then
            Return value
        Else
            Return Nothing
        End If
    End Function

    Public Shared Function ReadLine(ByVal value As String, ByVal splitter As Char, ByVal index As Integer) As String
        Dim str() As String = value.Split(splitter)
        Return str(index)
    End Function

    Public Shared Function ReadLine(ByVal value As String, ByVal splitters() As Char, ByVal indexes() As Integer) As String()
        Dim str() As String = value.Split(splitters)
        Dim strings() As String = Nothing
        For i As Integer = 0 To indexes.Count
            strings(i) = str(indexes(i))
        Next
        Return strings
    End Function

    Public Shared Function ReturnIcon(ByVal Path As String, ByVal Index As Integer, Optional ByVal small As Boolean = False) As Icon
        Dim bigIcon As Integer
        Dim smallIcon As Integer
        ExtractIcon(Path, Index, bigIcon, smallIcon, 1)
        If bigIcon = 0 Then
            ExtractIcon(Path, 0, bigIcon, smallIcon, 1)
        End If
        If bigIcon <> 0 Then
            If small = False Then
                Return Icon.FromHandle(bigIcon)
            Else
                Return Icon.FromHandle(smallIcon)
            End If
        Else
            Return Nothing
        End If
    End Function

End Class

I'm not entirely sure why I am being asked to cast App as a new instance of an App, since it is already cast as a new instance of that class, so I am very confused and really do not know how to solve this. Any help would be kindly appreciated.

Answer 1

You have not quoted the exact error message or the code at the line where the error occurs, but I suspect that the error relates to the collection, not the app.  When the error occurs, examine all the variables in the line that errors, and see if one of them is Nothing.   It appears that the collection is never being initialised.

Answer 2

Thank you for your effort. I found out that, as you said, the collection was not initialized as a new instance of AppDirectory.

Private Sub MainForm_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        App.AppCollection = New App.AppDirectory()
        Try
            App.GetAppDirectoryFile()
            App.GetApps()
        Catch ex As Exception
            MsgBox(ex.Message)
        End Try
        
    End Sub