ListView.OnAfterLabelEdit Method (LabelEditEventArgs)


Raises the AfterLabelEdit event.

Namespace:   System.Windows.Forms
Assembly:  System.Windows.Forms (in System.Windows.Forms.dll)

Protected Overridable Sub OnAfterLabelEdit (
	e As LabelEditEventArgs


Type: System.Windows.Forms.LabelEditEventArgs

A LabelEditEventArgs that contains the event data.

Raising an event invokes the event handler through a delegate. For more information, see Handling and Raising Events.

The OnAfterLabelEdit method also allows derived classes to handle the event without attaching a delegate. This is the preferred technique for handling the event in a derived class.

Notes to Inheritors:

When overriding OnAfterLabelEdit in a derived class, be sure to call the base class's OnAfterLabelEdit method so that registered delegates receive the event.

The following code example demonstrates how to use the AfterLabelEdit event to restrict a newly edited label to characters in the alphabet. The example uses the ASCIIEncoding class to obtain the ASCII character code of each character of the new label. If the character falls between the ASCII codes that represent numbers, the new label cannot be applied to the item. This example requires that you have created a ListView control on a form and added items to it. The example also requires that you have connected the AfterLabelEdit event to the event handler defined in the example code. In order to use the ASCIIEncoding class, your file must include the System.Text namespace.

Private Sub MyListView_AfterLabelEdit(ByVal sender As Object, ByVal e As System.Windows.Forms.LabelEditEventArgs) Handles listView1.AfterLabelEdit

   ' Determine if label is changed by checking to see if it is equal to Nothing.
   If e.Label Is Nothing Then
   End If
   ' ASCIIEncoding is used to determine if a number character has been entered.
   Dim AE As New ASCIIEncoding()
   ' Convert the new label to a character array.
   Dim temp As Char() = e.Label.ToCharArray()

   ' Check each character in the new label to determine if it is a number.
   Dim x As Integer
   For x = 0 To temp.Length - 1
      ' Encode the character from the character array to its ASCII code.
      Dim bc As Byte() = AE.GetBytes(temp(x).ToString())

      ' Determine if the ASCII code is within the valid range of numerical values.
      If bc(0) > 47 And bc(0) < 58 Then
         ' Cancel the event and return the lable to its original state.
         e.CancelEdit = True
         ' Display a MessageBox alerting the user that numbers are not allowed.
         MessageBox.Show("The text for the item cannot contain numerical values.")
         ' Break out of the loop and exit.
      End If
   Next x
End Sub

.NET Framework
Available since 1.1
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