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Control.OnDoubleClick Method

Raises the DoubleClick event.

[Visual Basic]
Protected Overridable Sub OnDoubleClick( _
   ByVal e As EventArgs _
)
[C#]
protected virtual void OnDoubleClick(
 EventArgs e
);
[C++]
protected: virtual void OnDoubleClick(
 EventArgs* e
);
[JScript]
protected function OnDoubleClick(
   e : EventArgs
);

Parameters

e
An EventArgs that contains the event data.

Remarks

Raising an event invokes the event handler through a delegate. For more information, see Raising an Event.

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

Example

[Visual Basic] 
' This example uses the DoubleClick event of a ListBox to load text files  
' listed in the ListBox into a TextBox control. This example
' assumes that the ListBox, named listBox1, contains a list of valid file 
' names with path and that this event handling method
' is connected to the DoublClick event of a ListBox control named listBox1.
' This example requires code access permission to access files.
Private Sub listBox1_DoubleClick(ByVal sender As Object, ByVal e As System.EventArgs) Handles listBox1.DoubleClick
    ' Get the name of the file to open from the ListBox.
    Dim file As [String] = listBox1.SelectedItem.ToString()

    Try
        ' Determine if the file exists before loading.
        If System.IO.File.Exists(file) Then
            ' Open the file and use a TextReader to read the contents into the TextBox.
            Dim myFile As New System.IO.FileInfo(listBox1.SelectedItem.ToString())
            Dim myData As System.IO.TextReader = myFile.OpenText()

            textBox1.Text = myData.ReadToEnd()
            myData.Close()
        End If
        ' Exception is thrown by the OpenText method of the FileInfo class.
    Catch
        MessageBox.Show("The file you specified does not exist.")
        ' Exception is thrown by the ReadToEnd method of the TextReader class.
    Catch
     MessageBox.Show("There was a problem loading the file into the TextBox. Ensure that the file is a valid text file.")
    End Try
End Sub

[C#] 
// This example uses the DoubleClick event of a ListBox to load text files
// listed in the ListBox into a TextBox control. This example
// assumes that the ListBox, named listBox1, contains a list of valid file
// names with path and that this event handling method
// is connected to the DoublClick event of a ListBox control named listBox1.
// This example requires code access permission to access files.
private void listBox1_DoubleClick(object sender, System.EventArgs e)
{
    // Get the name of the file to open from the ListBox.
    String file = listBox1.SelectedItem.ToString();

    try
    {
        // Determine if the file exists before loading.
        if (System.IO.File.Exists(file))
        {
            // Open the file and use a TextReader to read the contents into the TextBox.
            System.IO.FileInfo myFile = new System.IO.FileInfo(listBox1.SelectedItem.ToString());
            System.IO.TextReader myData = myFile.OpenText();;

            textBox1.Text = myData.ReadToEnd();
            myData.Close();
        }
    }
        // Exception is thrown by the OpenText method of the FileInfo class.
    catch(System.IO.FileNotFoundException)
    {
        MessageBox.Show("The file you specified does not exist.");
    }
        // Exception is thrown by the ReadToEnd method of the TextReader class.
    catch(System.IO.IOException)
    {
        MessageBox.Show("There was a problem loading the file into the TextBox. Ensure that the file is a valid text file.");
    }
}

[C++] 
// This example uses the DoubleClick event of a ListBox to load text files
// listed in the ListBox into a TextBox control. This example
// assumes that the ListBox, named listBox1, contains a list of valid file
// names with path and that this event handling method
// is connected to the DoublClick event of a ListBox control named listBox1.
// This example requires code access permission to access files.
private:
void listBox1_DoubleClick(Object* /*sender*/, System::EventArgs* /*e*/)
{
   // Get the name of the file to open from the ListBox.
   String* file = listBox1->SelectedItem->ToString();
   try
   {
      // Determine if the file exists before loading.
      if (System::IO::File::Exists(file))
      {
         // Open the file and use a TextReader to read the contents into the TextBox.
         System::IO::FileInfo* myFile = new System::IO::FileInfo(listBox1->SelectedItem->ToString());
         System::IO::TextReader* myData = myFile->OpenText();;

         textBox1->Text = myData->ReadToEnd();
         myData->Close();
      }
   }
   // Exception is thrown by the OpenText method of the FileInfo class.
   catch(System::IO::FileNotFoundException*)
   {
      MessageBox::Show(S"The file you specified does not exist.");
   }
   // Exception is thrown by the ReadToEnd method of the TextReader class.
   catch(System::IO::IOException*)
   {
      MessageBox::Show(S"There was a problem loading the file into the TextBox. Ensure that the file is a valid text file.");
   }
}

[JScript] No example is available for JScript. To view a Visual Basic, C#, or C++ example, click the Language Filter button Language Filter in the upper-left corner of the page.

Requirements

Platforms: Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 family

See Also

Control Class | Control Members | System.Windows.Forms Namespace | DoubleClick

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