Public Event SelectedIndexChanged As EventHandler

Dim instance As ListBox
Dim handler As EventHandler

AddHandler instance.SelectedIndexChanged, handler

public event EventHandler SelectedIndexChanged

public:
event EventHandler^ SelectedIndexChanged {
    void add (EventHandler^ value);
    void remove (EventHandler^ value);
}

/** @event */
public void add_SelectedIndexChanged (EventHandler value)

/** @event */
public void remove_SelectedIndexChanged (EventHandler value)

JScript 支持使用事件，但不支持进行新的声明。

Private Sub listBox1_SelectedIndexChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles listBox1.SelectedIndexChanged
   ' Get the currently selected item in the ListBox.
   Dim curItem As String = listBox1.SelectedItem.ToString()

   ' Find the string in ListBox2.
   Dim index As Integer = listBox2.FindString(curItem)
   ' If the item was not found in ListBox 2 display a message box, otherwise select it in ListBox2.
   If index = -1 Then
      MessageBox.Show("Item is not available in ListBox2")
   Else
      listBox2.SetSelected(index, True)
   End If
End Sub

private void listBox1_SelectedIndexChanged(object sender, System.EventArgs e)
{
   // Get the currently selected item in the ListBox.
   string curItem = listBox1.SelectedItem.ToString();

   // Find the string in ListBox2.
   int index = listBox2.FindString(curItem);
   // If the item was not found in ListBox 2 display a message box, otherwise select it in ListBox2.
   if(index == -1)
      MessageBox.Show("Item is not available in ListBox2");
   else
      listBox2.SetSelected(index,true);
}

private:
   void listBox1_SelectedIndexChanged( Object^ /*sender*/, System::EventArgs^ /*e*/ )
   {
      // Get the currently selected item in the ListBox.
      String^ curItem = listBox1->SelectedItem->ToString();

      // Find the string in ListBox2.
      int index = listBox2->FindString( curItem );

      // If the item was not found in ListBox 2 display a message box,
      //  otherwise select it in ListBox2.
      if ( index == -1 )
            MessageBox::Show( "Item is not available in ListBox2" );
      else
            listBox2->SetSelected( index, true );
   }

private void listBox1_SelectedIndexChanged(Object sender, 
    System.EventArgs e)
{
    // Get the currently selected item in the ListBox.
    String curItem = listBox1.get_SelectedItem().ToString();
    // Find the string in ListBox2.
    int index = listBox2.FindString(curItem);
    // If the item was not found in ListBox 2 display a message box, 
    // otherwise select it in ListBox2.
    if (index == -1) {
        MessageBox.Show("Item is not available in ListBox2");
    }
    else {
        listBox2.SetSelected(index, true);
    }
} //listBox1_SelectedIndexChanged