Geneate/Create ArrayCollection dynamically

var resultArr:ArrayCollection = new ArrayCollection(e.result as Array);
var careeListData:ArrayCollection = new ArrayCollection();
var resultArray:Array = new Array();
if((resultArr.length > 0) && (resultArr[0]["whoForId"] != null)){

for(var l=0; l < resultArr.length; l++){

resultArray.push({label:resultArr[l]["careeName"], data:resultArr[l]["whoForId"]})

}
careeListData = resultArray as Object;
}

Combobox with change event to get the selected item value

In the script add the following

private var listData:ArrayCollection = new ArrayCollection(
[{label:"Arun Kumar", data:"3"},
{label:"John Jose", data:"1"},
{label:"Mary Dam", data:"2"}]);
private function getSelectedCaree(event:Event):void
{
trace(event.currentTarget.selectedItem.data);
}

In the MXML add the following to show the combo-box with change event

mx:ComboBox id="comboList" change="getSelectedCaree(event)" fontSize="15" x="1000" y="50" dataProvider="{listData}"
/mx:ComboBox