How to obtain the ListItem inside a CheckBoxList which triggered the postback?

I have two CheckBoxLists and I need to be able to set the ListItems selected in one of the CheckBoxList depending on the items selected in the other CheckBoxList.

How can I know which ListItem inside a CheckBoxList had issued the postback? The method must be run at server.

SOLUTION UPDATE:

Final solution i used (thanks to Four):

protected void CheckBoxList1_SelectedIndexChanged(object sender, EventArgs e)
{
    var selectedItem = CheckBoxList1.SelectedItem;
}

Where selectedItem is the ListItem that was click开发者_运维百科ed.

Set the AutoPostBack property to True and then make and changes you need to do on the server: How to use AutoPostBack feature in CheckBoxList

<asp:CheckBoxList   
         ID="CheckBoxList1"  
         runat="server"  
         AutoPostBack="true"  
         OnSelectedIndexChanged="CheckBoxList1_SelectedIndexChnaged"  
> 

To see which ListItems have been checked, you can iterate through the CheckBoxList as follows:

protected void CheckBoxList1_SelectedIndexChnaged(object sender, System.EventArgs e)  
{  
    Label1.Text = "You Selected:<br /><i>";  
    foreach (ListItem li in CheckBoxList1.Items)  
    {  
        if (li.Selected == true)  
        {  
            Label1.Text += li.Text + "<br />";  
        }  
    }  
    Label1.Text += "</i>";  
}

To get the value of the ListItem that was checked without iterating through all ListItems, you can do the following:

protected void CheckBoxList1_SelectedIndexChanged(object sender, EventArgs e)
{
    CheckBoxList list = (CheckBoxList)sender;
    string[] control = Request.Form.Get("__EVENTTARGET").Split('$');
    int index = control.Length - 1;
    ListItem li = (ListItem)list.Items[Int32.Parse(control[index])];
}

At this point you'll have the actual ListItem that was checked and you can do with it whatever you please.

Much simpler:

var selectedItem = CheckBoxList1.SelectedItem;