VB.NET

VB.NET RSS

Problems instering items into a listview

Please support our VB.NET advertiser: Intel Parallel Studio Home

•

Join Date: Dec 2007

Posts: 31

Reputation: AaronASterling is an unknown quantity at this point

Solved Threads: 5

AaronASterling AaronASterling is offline

Offline

Light Poster

Problems instering items into a listview

Dec 24th, 2007

Hello All,

I have a user define class,

 Help with Code Tags 
 vb Syntax (Toggle Plain Text) 
<Serializable()> Public Class City
 
    Public Name As String = ""
    Public State As String = ""
    Public URL As String = ""
 
    Public Sub New(ByVal state As String, ByVal name As String, ByVal url As String)
 
       me.State = state
       me.Name = name
       me.URL = url
 
    End Sub
 
    Public Function isValid() As Boolean
 
        If me.Name <> "" And _
           me.State <> "" And _
           me.URL <> "" Then
 
            Return True
 
        Else
 
            Return False
 
        End If
 
    End Function
 
    Public Function ToSmallListViewItem() As ListViewItem
 
        Dim item As New ListViewItem
 
        item.SubItems.Add(me.State)
        item.SubItems.Add(me.Name)
        item.Tag = Me
 
        Return item
 
    End Function
 
End Class
<Serializable()> Public Class City

    Public Name As String = ""
    Public State As String = ""
    Public URL As String = ""

    Public Sub New(ByVal state As String, ByVal name As String, ByVal url As String)

       me.State = state
       me.Name = name
       me.URL = url

    End Sub
    
    Public Function isValid() As Boolean

        If me.Name <> "" And _
           me.State <> "" And _
           me.URL <> "" Then

            Return True

        Else

            Return False

        End If

    End Function

    Public Function ToSmallListViewItem() As ListViewItem

        Dim item As New ListViewItem

        item.SubItems.Add(me.State)
        item.SubItems.Add(me.Name)
        item.Tag = Me

        Return item

    End Function

End Class

From the last member function you can guess that I want to display lists of instances of this class in a listview control. Here is the code. It is a member of the main form of the application that owns the listview

 Help with Code Tags 
 vb Syntax (Toggle Plain Text) 
 
Private Sub LoadMasterCityList()
 
        lvMasterCityList.Items.Clear()
 
       'master cities is an element of a wrapper class for List(Of City)
       'even when I bypass the wrapper and deal directly with the list as below
       'it doesn't work
 
        MasterCities = Cities.Load(Settings.strMasterCityListFile) 'this just loads from a file
        For Each CityItem As City In MasterCities.CityList
 
            'this is the listview control
            lvMasterCityList.Items.Add(CityItem.ToSmallListViewItem())
 
        Next
Private Sub LoadMasterCityList()

        lvMasterCityList.Items.Clear()
       
       'master cities is an element of a wrapper class for List(Of City)
       'even when I bypass the wrapper and deal directly with the list as below
       'it doesn't work

        MasterCities = Cities.Load(Settings.strMasterCityListFile) 'this just loads from a file
        For Each CityItem As City In MasterCities.CityList

            'this is the listview control
            lvMasterCityList.Items.Add(CityItem.ToSmallListViewItem())

        Next

The problem is that the listview doesn't display the input. It has two columns as required by [inlinecode=vb]City.ToSmallListViewItem()[/inlinecode] method and is set to visible. It creates a scrollbar and I can highlight empty elements of it and scroll around. I just cant see the text. I am positive that the data is valid as it is sent to the [inlinecode=vb]LoadMasterCityList[/inlinecode] method, for example I have used [inlinecode=vb]MsgBox[/inlinecode]'s to print the contents of each [inlinecode=vb]CityItem[/inlinecode] both before and after the call to [inlinecode=vb]CityItem.ToSmallListViewItem()[/inlinecode] so I am sure that the data is write. Does anyone have any idea what can cause this behavior? I am stumped! All I have been able to find is that setting the checkbox property to true can cause a listbox too not render but I am not doing that and that is only applicable if its in large image or small image mode. It's in list mode anyway so thats not it.

Thanks in advance
Aaron