Data grid combo box

Question

how can i add a combo box in to the Data grid when i click the add button.
when i add  the second row what i have selected before is refreshed.
please help me

Answer 1

The data property of the item renderer corresponds to the
item the item renderer renders (a lot of repetitions here... :-).
But when your application starts, the data property of your
item renderer is null. Still, the code is executed. So you get a
null pointer exception.
How to solve this problem ?
Use databinding within the item renderer in order to detect
the data value change from null to an object value:
<mx:Binding source="{this.data}"
destination="onDataChanged" />
private function set onDataChanged(value:Object):void
if(value)
// Do something if value is non-null
Voila !
No more errors.
Since the item has a type in the dataprovider of my datagrids
in my projects, I cast the data property to an explicit type before
accessing the item properties:
E.g
(this.data as Product).ISBN