Update selected Listview Subitem with Property Set by another Form

[berkleyp]

Ok, I am trying to update the value of SubItem(4) of the selected listview item using a property which is set by another form.

 

Here are the forms I have:

FormA (Form with ListView1)

FormB (Form with TextBox1 that sets Class1.Value1)

 

What I do is populate ListView1 based on other selections the user makes on FormA. If they want to change the value for SubItem(4) they click a button which launches FormB.

 

FormA Sets a property to the ListView1 Selected Index with the following code:

 

   Private Sub ListView1 _SelectedIndexChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles ListView1.SelectedIndexChanged

       Dim lstrSelected As String

       If ListView1.SelectedItems.Count > 0 Then

           cmdEdit.Enabled = True
           cmdRemove.Enabled = True

           Dim selNdx = Me.ListView1.SelectedIndices(0)

           If selNdx >= 0 Then

               lstrSelected = ListView1.Items(selNdx).Text

               Class1.Selected = lstrSelected

           End If

       End If

   End Sub

 

FormA then does the following when clicking the "Edit" button:

 

   Private Sub cmdEdit_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles cmdEdit.Click

       Class1.Value1= CInt(ListView1.SelectedItems(0).SubItems(4).Text)

       FormB.Show()

   End Sub

 

FormB has the following Code:

   Private Sub cmdOK_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles cmdOK.Click

       Class1.Value1 = Me.TextBox1 .Text

       Close()

       FormA.UpdateValue1()

   End Sub

 

FormA is trying to us the UpdateValue1 sub which looks like this:

   Public Sub UpdateValue1()

       Dim lvwItem As String

       lvwItem = Class1.Selected

       Me.ListView1.Items(lvwItem).SubItems(4).Text = Class1.Value1 

   End Sub

 

When I get to the UpdateValue1 all the correct values are set for the Properties but I keep getting the following error: "Object reference not set to an instance of an object."

 

Now, I do not close FormA when launching FormB so I am confused as to why its stating I need to reference an Instance of an Object. To be totally honest, I am still really new with the whole programming thing. I have written some VBA (please dont laugh) for Excel. This is my first full VS2005 project.

 

Any help would be greatly appreciated.

[snarfblam]

Which line are you getting the error on? Also, you should be able to hover the mouse over any identifier and a tooltip should pop up with the variable's or property's value.

[berkleyp]

I get the error on this line:

 Me.ListView1.Items(lvwItem).SubItems(4).Text = Class1.Value1  

 

And I am able to mouse over each variable and see the values of each. They all contain the correct values.

[snarfblam]

Are you sure that Class1 has a value? I think an invalid/null index/key would throw an ArgumentException, and I don't know what else it could be.

[berkleyp]

Yeah, Class1 has a value. I think I know what I am going to do to fix it though. I am going to store all the values in ListView1 as local variables then remove the item before i do the update. After that I will just readd with new value. I think this will be the easiest way to get around my issue.

 

Sorry it took so long to respond. Was fighting other battles with the application.