ListView.OnAfterLabelEdit(LabelEditEventArgs) 方法

定义

命名空间:

System.Windows.Forms

程序集:

System.Windows.Forms.dll

引发 AfterLabelEdit 事件。

protected:
 virtual void OnAfterLabelEdit(System::Windows::Forms::LabelEditEventArgs ^ e);

protected virtual void OnAfterLabelEdit (System.Windows.Forms.LabelEditEventArgs e);

abstract member OnAfterLabelEdit : System.Windows.Forms.LabelEditEventArgs -> unit
override this.OnAfterLabelEdit : System.Windows.Forms.LabelEditEventArgs -> unit

Protected Overridable Sub OnAfterLabelEdit (e As LabelEditEventArgs)

参数

e

LabelEditEventArgs

包含事件数据的 LabelEditEventArgs。

示例

下面的代码示例演示如何使用 AfterLabelEdit 事件将新编辑的标签限制为字母表中的字符。 该示例使用 ASCIIEncoding 类获取新标签的每个字符的 ASCII 字符代码。 如果字符位于表示数字的 ASCII 代码之间，则无法将新标签应用于该项。 此示例要求你在窗体上创建了一个 ListView 控件，并为其添加了项。 此示例还要求已将 AfterLabelEdit 事件连接到示例代码中定义的事件处理程序。 若要使用 ASCIIEncoding 类，文件必须包含 System.Text 命名空间。

private:
   void MyListView_AfterLabelEdit( Object^ /*sender*/, System::Windows::Forms::LabelEditEventArgs^ e )
   {
      // Determine if label is changed by checking for 0.
      if ( e->Label == nullptr )
               return;

      // ASCIIEncoding is used to determine if a number character has been entered.
      ASCIIEncoding^ AE = gcnew ASCIIEncoding;

      // Convert the new label to a character array.
      array<Char>^temp = e->Label->ToCharArray();

      // Check each character in the new label to determine if it is a number.
      for ( int x = 0; x < temp->Length; x++ )
      {
         // Encode the character from the character array to its ASCII code.
         array<Byte>^bc = AE->GetBytes( temp[ x ].ToString() );

         // Determine if the ASCII code is within the valid range of numerical values.
         if ( bc[ 0 ] > 47 && bc[ 0 ] < 58 )
         {
            // 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.
            return;
         }
      }
   }

private void MyListView_AfterLabelEdit(object sender, System.Windows.Forms.LabelEditEventArgs e)
{
 
   // Determine if label is changed by checking for null.
   if (e.Label == null)
      return;

   // ASCIIEncoding is used to determine if a number character has been entered.
   ASCIIEncoding AE = new ASCIIEncoding();
   // Convert the new label to a character array.
   char[] temp = e.Label.ToCharArray();

   // Check each character in the new label to determine if it is a number.
   for(int x=0; x < temp.Length; x++)
   {
      // Encode the character from the character array to its ASCII code.
      byte[] bc = AE.GetBytes(temp[x].ToString());
   
      // Determine if the ASCII code is within the valid range of numerical values.
      if(bc[0] > 47 && bc[0] < 58)
      {
         // 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.
         return;
      }
   }
}

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
      Return
   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.
         Return
      End If
   Next x
End Sub

注解

引发事件时，将通过委托调用事件处理程序。 有关详细信息，请参阅 处理和引发事件。

OnAfterLabelEdit 方法还允许派生类对事件进行处理而不必附加委托。 这是在派生类中处理事件的首选技术。

继承者说明

在派生类中重写 OnAfterLabelEdit(LabelEditEventArgs) 时，一定要调用基类的 OnAfterLabelEdit(LabelEditEventArgs) 方法，以便已注册的委托对事件进行接收。

另请参阅

• AfterLabelEdit
• LabelEditEventArgs