ListBox.GetSelected(Int32) 方法

定义

返回一个值,该值指示是否选定了指定的项。Returns a value indicating whether the specified item is selected.

public:
 bool GetSelected(int index);
public bool GetSelected (int index);
member this.GetSelected : int -> bool
Public Function GetSelected (index As Integer) As Boolean

参数

index
Int32

项的从零开始的索引,根据该索引确定该项是否被选定。The zero-based index of the item that determines whether it is selected.

返回

如果当前在 ListBox 中选定了指定的项,则为 true;否则为 falsetrue if the specified item is currently selected in the ListBox; otherwise, false.

异常

index 参数或者小于零,或者大于或等于 Count 类的 ListBox.ObjectCollection 属性的值。The index parameter is less than zero or greater than or equal to the value of the Count property of the ListBox.ObjectCollection class.

示例

下面的代码示例演示如何使用 GetSelected 方法来确定 ListBox 中选择了哪些项,以便选择未选择的项并取消选择所选的项。The following code example demonstrates how to use the GetSelected method to determine which items in a ListBox are selected in order to select the items that are not selected and deselect the items that are selected. 该示例还演示了如何使用 SelectionMode 属性使某个 ListBox 具有多个选定项,并使用 Sorted 属性演示如何自动对 ListBox 中的项进行排序。The example also demonstrates using the SelectionMode property to enable a ListBox to have more than one selected item and uses the Sorted property to demonstrate how to sort items in a ListBox automatically. 此示例要求已将名为 listBox1ListBox添加到窗体中,并且该示例中定义的 InitializeMyListBox 方法是从窗体的 Load 事件中调用的。This example requires that a ListBox, named listBox1, has been added to a form and that the InitializeMyListBox method defined in the example is called from the Load event of the form.

private:
   void InitializeMyListBox()
   {
      // Add items to the ListBox.
      listBox1->Items->Add( "A" );
      listBox1->Items->Add( "C" );
      listBox1->Items->Add( "E" );
      listBox1->Items->Add( "F" );
      listBox1->Items->Add( "G" );
      listBox1->Items->Add( "D" );
      listBox1->Items->Add( "B" );

      // Sort all items added previously.
      listBox1->Sorted = true;

      // Set the SelectionMode to select multiple items.
      listBox1->SelectionMode = SelectionMode::MultiExtended;

      // Select three initial items from the list.
      listBox1->SetSelected( 0, true );
      listBox1->SetSelected( 2, true );
      listBox1->SetSelected( 4, true );

      // Force the ListBox to scroll back to the top of the list.
      listBox1->TopIndex = 0;
   }

   void InvertMySelection()
   {
      // Loop through all items the ListBox.
      for ( int x = 0; x < listBox1->Items->Count; x++ )
      {
         // Select all items that are not selected,
         // deselect all items that are selected.
         listBox1->SetSelected( x,  !listBox1->GetSelected( x ) );
      }
      listBox1->TopIndex = 0;
   }
private void InitializeMyListBox()
{
   // Add items to the ListBox.
   listBox1.Items.Add("A");
   listBox1.Items.Add("C");
   listBox1.Items.Add("E");
   listBox1.Items.Add("F");
   listBox1.Items.Add("G");
   listBox1.Items.Add("D");
   listBox1.Items.Add("B");

   // Sort all items added previously.
   listBox1.Sorted = true;

   // Set the SelectionMode to select multiple items.
   listBox1.SelectionMode = SelectionMode.MultiExtended;

   // Select three initial items from the list.
   listBox1.SetSelected(0,true);
   listBox1.SetSelected(2,true);
   listBox1.SetSelected(4,true);

   // Force the ListBox to scroll back to the top of the list.
   listBox1.TopIndex=0;
}

private void InvertMySelection()
{
   // Loop through all items the ListBox.
   for (int x = 0; x < listBox1.Items.Count; x++)
   {
      // Determine if the item is selected.
      if(listBox1.GetSelected(x) == true)
         // Deselect all items that are selected.
         listBox1.SetSelected(x,false);      
      else
         // Select all items that are not selected.
         listBox1.SetSelected(x,true);
   }
   // Force the ListBox to scroll back to the top of the list.
   listBox1.TopIndex=0;
}
Private Sub InitializeMyListBox()
   ' Add items to the ListBox.
   listBox1.Items.Add("A")
   listBox1.Items.Add("C")
   listBox1.Items.Add("E")
   listBox1.Items.Add("F")
   listBox1.Items.Add("G")
   listBox1.Items.Add("D")
   listBox1.Items.Add("B")

   ' Sort all items added previously.
   listBox1.Sorted = True

   ' Set the SelectionMode to select multiple items.
   listBox1.SelectionMode = SelectionMode.MultiExtended

   ' Select three initial items from the list.
   listBox1.SetSelected(0, True)
   listBox1.SetSelected(2, True)
   listBox1.SetSelected(4, True)

   ' Force the ListBox to scroll back to the top of the list.
   listBox1.TopIndex = 0
End Sub

Private Sub InvertMySelection()

   Dim x As Integer
   ' Loop through all items the ListBox.
   For x = 0 To listBox1.Items.Count - 1

      ' Determine if the item is selected.
      If listBox1.GetSelected(x) = True Then
         ' Deselect all items that are selected.
         listBox1.SetSelected(x, False)
      Else
         ' Select all items that are not selected.
         listBox1.SetSelected(x, True)
      End If
   Next x
   ' Force the ListBox to scroll back to the top of the list.
   listBox1.TopIndex = 0
End Sub

注解

您可以使用此方法快速确定是否选择了指定的项。You can use this method to quickly determine whether a specified item is selected. 当选择多重选择 ListBox 中的特定项时,此方法非常有用。This method is useful when a specific operation needs to be performed when a specific item in a multiple-selection ListBox is selected.

适用于