how to lock check items in listview - vb.net

Question

the code is perfect, but how can i lock the check items (ONLY REQUIRED items) in listview?
lvFees.Columns.Add("Fee", 120)
lvFees.Columns.Add("Amount", 76)
connect()
rec.Open("select * from tablePayments where sem='" & cboSem.Text & "'", con, 3, 3)
If rec.RecordCount <> 0 Then
Dim i As Integer = 0
Do Until rec.EOF
lvFees.Items.Add(rec("payname").Value)
lvFees.Items(i).SubItems.Add(rec("amount").Value)
If rec("paytype").Value = "REQUIRED" Then ' the paytype has two options, the "REQUIRED" and OPTIONAL.
lvFees.Items(i).Checked = True
End If
rec.MoveNext()
i = i + 1
Loop
End If
rec.Close()
con.Close()
i want to lock the check of all REQUIRED item, while letting the user to check and uncheck the OPTIONAL items

Answer 1

I'm sure there are lower-level ways of accomplishing this, such as by inheriting the ListView class and overriding some of its behavior, but for a simpler approach, you could simply force the value in the ItemChecked event. You could use the Tag property of each item in the list to keep track of its "locked" value. For instance, if you loaded a ListView control with three items like this:
ListView1.Items.Add("Unlocked")
ListView1.Items.Add("Locked On").Tag = True
ListView1.Items(1).Checked = True
ListView1.Items.Add("Locked Off").Tag = False
And then put code like this in the ItemChecked event handler:
Private Sub ListView1_ItemChecked(sender As Object, e As ItemCheckedEventArgs) Handles ListView1.ItemChecked
If e.Item.Tag IsNot Nothing Then
e.Item.Checked = DirectCast(e.Item.Tag, Boolean)
End If
End Sub
Then that makes it so the check box of the first item can be altered by the user, but the other two items are locked in their respective states.