ListBox.SetSelected(Int32, Boolean) Method

Reference

Definition

Namespace:: System.Windows.Forms

Assembly:: System.Windows.Forms.dll

Important

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Selects or clears the selection for the specified item in a ListBox.

public:
 void SetSelected(int index, bool value);

public void SetSelected (int index, bool value);

member this.SetSelected : int * bool -> unit

Public Sub SetSelected (index As Integer, value As Boolean)

Parameters

index: Int32

The zero-based index of the item in a ListBox to select or clear the selection for.

value: Boolean

true to select the specified item; otherwise, false.

Exceptions

ArgumentOutOfRangeException

The specified index was outside the range of valid values.

InvalidOperationException

The SelectionMode property was set to None.

Examples

The following code example demonstrates how to create a ListBox control that displays multiple items in columns and can have more than one item selected in the control's list. The code for the example adds 50 items to the ListBox using the Add method of the ListBox.ObjectCollection class and then selects three items from the list using the SetSelected method. The code then displays values from the ListBox.SelectedObjectCollection collection (through the SelectedItems property) and the ListBox.SelectedIndexCollection (through the SelectedIndices property). This example requires that the code is located in and called from a Form.

void button1_Click( Object^ /*sender*/, System::EventArgs^ /*e*/ )
{
   
   // Create an instance of the ListBox.
   ListBox^ listBox1 = gcnew ListBox;
   
   // Set the size and location of the ListBox.
   listBox1->Size = System::Drawing::Size( 200, 100 );
   listBox1->Location = System::Drawing::Point( 10, 10 );
   
   // Add the ListBox to the form.
   this->Controls->Add( listBox1 );
   
   // Set the ListBox to display items in multiple columns.
   listBox1->MultiColumn = true;
   
   // Set the selection mode to multiple and extended.
   listBox1->SelectionMode = SelectionMode::MultiExtended;
   
   // Shutdown the painting of the ListBox as items are added.
   listBox1->BeginUpdate();
   
   // Loop through and add 50 items to the ListBox.
   for ( int x = 1; x <= 50; x++ )
   {
      listBox1->Items->Add( String::Format( "Item {0}", x ) );

   }
   listBox1->EndUpdate();
   
   // Select three items from the ListBox.
   listBox1->SetSelected( 1, true );
   listBox1->SetSelected( 3, true );
   listBox1->SetSelected( 5, true );
   
   #if defined(DEBUG)
   // Display the second selected item in the ListBox to the console.
   System::Diagnostics::Debug::WriteLine( listBox1->SelectedItems[ 1 ] );
   
   // Display the index of the first selected item in the ListBox.
   System::Diagnostics::Debug::WriteLine( listBox1->SelectedIndices[ 0 ] );
   #endif
}

private void button1_Click(object sender, System.EventArgs e)
{
   // Create an instance of the ListBox.
   ListBox listBox1 = new ListBox();
   // Set the size and location of the ListBox.
   listBox1.Size = new System.Drawing.Size(200, 100);
   listBox1.Location = new System.Drawing.Point(10,10);
   // Add the ListBox to the form.
   this.Controls.Add(listBox1);
   // Set the ListBox to display items in multiple columns.
   listBox1.MultiColumn = true;
   // Set the selection mode to multiple and extended.
   listBox1.SelectionMode = SelectionMode.MultiExtended;
 
   // Shutdown the painting of the ListBox as items are added.
   listBox1.BeginUpdate();
   // Loop through and add 50 items to the ListBox.
   for (int x = 1; x <= 50; x++)
   {
      listBox1.Items.Add("Item " + x.ToString());
   }
   // Allow the ListBox to repaint and display the new items.
   listBox1.EndUpdate();
      
   // Select three items from the ListBox.
   listBox1.SetSelected(1, true);
   listBox1.SetSelected(3, true);
   listBox1.SetSelected(5, true);

   // Display the second selected item in the ListBox to the console.
   System.Diagnostics.Debug.WriteLine(listBox1.SelectedItems[1].ToString());
   // Display the index of the first selected item in the ListBox.
   System.Diagnostics.Debug.WriteLine(listBox1.SelectedIndices[0].ToString());             
}

Private Sub button1_Click(sender As Object, e As System.EventArgs)
    ' Create an instance of the ListBox.
    Dim listBox1 As New ListBox()
    ' Set the size and location of the ListBox.
    listBox1.Size = New System.Drawing.Size(200, 100)
    listBox1.Location = New System.Drawing.Point(10, 10)
    ' Add the ListBox to the form.
    Me.Controls.Add(listBox1)
    ' Set the ListBox to display items in multiple columns.
    listBox1.MultiColumn = True
    ' Set the selection mode to multiple and extended.
    listBox1.SelectionMode = SelectionMode.MultiExtended
    
    ' Shutdown the painting of the ListBox as items are added.
    listBox1.BeginUpdate()
    ' Loop through and add 50 items to the ListBox.
    Dim x As Integer
    For x = 1 To 50
        listBox1.Items.Add("Item " & x.ToString())
    Next x
    ' Allow the ListBox to repaint and display the new items.
    listBox1.EndUpdate()
    
    ' Select three items from the ListBox.
    listBox1.SetSelected(1, True)
    listBox1.SetSelected(3, True)
    listBox1.SetSelected(5, True)
       
    ' Display the second selected item in the ListBox to the console.
    System.Diagnostics.Debug.WriteLine(listBox1.SelectedItems(1).ToString())
    ' Display the index of the first selected item in the ListBox.
    System.Diagnostics.Debug.WriteLine(listBox1.SelectedIndices(0).ToString())
End Sub

Remarks

You can use this property to set the selection of items in a multiple-selection ListBox. To select an item in a single-selection ListBox, use the SelectedIndex property.

Applies to

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