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The SelectedIndexChanged event occurs when the SelectedIndex has just changed.

The SelectedIndexChanged event does not fire unless the AutoPostBack property is True .

The SelectedIndexChanged event handler receives two arguments:

  1. The RadDropDownList that is loading items. This argument is of type object, but can be cast to the RadDropDownList type.

  2. An EventArgs object. This object has the following properties for identifying what has changed:

    • Index is the index of the item that was just selected.

    • Text is the text of the item that was just selected.

    • Value is the value of the item that was just selected.

Use the SelectedIndexChanged event handler to respond in server-side code when the user changes the current selection:

<telerik:RadDropDownList RenderMode="Lightweight" ID="RadDropDownList1"

        protected void RadDropDownList1_SelectedIndexChanged(object sender, DropDownListEventArgs e)
            Label1.Text = "You selected " + e.Text + " item";

        Private Sub RadDropDownList1_SelectedIndexChanged(ByVal o As Object, ByVal e As Telerik.Web.UI.DropDownListEventArgs)

            Label1.Text = "You selected " + e.Text + " item"

        End Sub

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