DropDownList.SelectedIndexChanged

[sara_22]

I have 2 dropdown lists on one page. A selection from the first list
determines what gets listed in the second list.
but the problem nothing appears in list2.


the following code

Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
'Put user code to initialize the page here
DropDownList1.Items.Add("a")
DropDownList1.Items.Add("b")
End Sub

Private Sub DropDownList1_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles DropDownList1.SelectedIndexChanged
DropDownList2.Items.Clear()
Dim a As Integer
a = DropDownList1.SelectedIndex
If a = 0 Then
DropDownList2.Items.Add("selected a")
Else
DropDownList2.Items.Add("selected b")

End If
End Sub
plz help me
thanx
sara

[Nikhil Aggarwal]

Set the AutoPostBack property for DropDownList1 control to true.

If this property is set to false then the function DropDownList1_SelectedIndexChanged will not be called at all.

~Nikhil

[sara_22]

Thank u very much

[sara_22]

Dear Nikhil
the proble was solved but still i have another problem
with every selection for list2, the items are duplicated in list 1.

[Nikhil Aggarwal]

Im guessing you are populating List 1 on the PageLoad event. What is happening is that items are bieng re-added to List1 every time the Page makes a round trip to the server.

Place the List1 data population code in a If block where you check if the page has been posted back or not.

If Not IsPostBack Then
            'Code to add items to list 1
            DropDownList1.Items.Add("1")
            DropDownList1.Items.Add("2")
            DropDownList1.Items.Add("3")
End If

~Nikhil

[sara_22]

Dear Nikhil
it is working good now
thank u very much for ur help