<?xml version="1.0" encoding="utf-8"?>
<!-- http://blog.flexexamples.com/2008/02/28/displaying-the-sort-arrow-in-a-flex-datagrid-control-without-having-to-click-a-column/ -->
<mx:Application name="DataGrid_dataProvider_sort_fields_test">
        xmlns:mx="http://www.adobe.com/2006/mxml"
        layout="vertical"
        verticalAlign="middle"
        backgroundColor="white">
 
    <mx:Script>
        <![CDATA[
            import mx.collections.Sort;
            import mx.collections.SortField;
 
            private function init():void {
                arrColl.sort = new Sort();
                arrColl.sort.fields = [new SortField("idx", false, true)];
                arrColl.refresh();
            }
        ]]>
    </mx:Script>
 
    <mx:ArrayCollection id="arrColl">
        <mx:source>
            <mx:Array>
                <mx:Object idx="1" c1="One.1" c2="One.2" />
                <mx:Object idx="2" c1="Two.1" c2="Two.2" />
                <mx:Object idx="3" c1="Three.1" c2="Three.2" />
                <mx:Object idx="4" c1="Four.1" c2="Four.2" />
                <mx:Object idx="5" c1="Five.1" c2="Five.2" />
                <mx:Object idx="6" c1="Six.1" c2="Six.2" />
                <mx:Object idx="7" c1="Seven.1" c2="Seven.2" />
                <mx:Object idx="8" c1="Eight.1" c2="Eight.2" />
                <mx:Object idx="9" c1="Nine.1" c2="Nine.2" />
                <mx:Object idx="10" c1="Ten.1" c2="Ten.2" />
                <mx:Object idx="11" c1="Eleven.1" c2="Eleven.2" />
                <mx:Object idx="12" c1="Twelve.1" c2="Twelve.2" />
                <mx:Object idx="13" c1="Thirteen.1" c2="Thirteen.2" />
            </mx:Array>
        </mx:source>
    </mx:ArrayCollection>
 
    <mx:DataGrid id="dataGrid"
            dataProvider="{arrColl}"
            creationComplete="init();">
        <mx:columns>
            <mx:DataGridColumn dataField="idx" />
            <mx:DataGridColumn dataField="c1" />
            <mx:DataGridColumn dataField="c2" />
        </mx:columns>
    </mx:DataGrid>
 
</mx:Application>

<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" layout="vertical" verticalAlign="middle" backgroundColor="white" creationComplete="init()">
 
    <mx:Script>
        <![CDATA[
            import mx.collections.SortField;
            import mx.collections.Sort;
            import mx.collections.ArrayCollection;
 
            [Bindable]
            private var arrColl:ArrayCollection;
 
            /** This method gets called by the main mx:Application tag and initializes/populates the ArrayCollection object with a bunch of random numbers. */
            private function init():void {
                var i:int;
 
                /* Initialize and populate the ArrayCollection object. */
                arrColl = new ArrayCollection();
                for (i = 0; i < 20; i++) {
                    arrColl.addItem({data:getRandomNumber().toFixed(4)});
                }
            }
 
            /** This method returns a random floating-point number between 0 and 10000. */
            private function getRandomNumber():Number {
                return Math.random() * 10000;
            }
 
            /** This method gets called by the Button control's click handler and creates a new SortField and Sort object which are used to sort the ArrayCollection. */
            private function button_click():void {
                /* Create the SortField object for the "data" field in the ArrayCollection object, and make sure we do a numeric sort. */
                var dataSortField:SortField = new SortField();
                dataSortField.name = "data";
                dataSortField.numeric = true;
 
                /* Create the Sort object and add the SortField object created earlier to the array of fields to sort on. */
                var numericDataSort:Sort = new Sort();
                numericDataSort.fields = [dataSortField];
 
                /* Set the ArrayCollection object's sort property to our custom sort, and refresh the ArrayCollection. */
                arrColl.sort = numericDataSort;
                arrColl.refresh();
            }
        ]]>
    </mx:Script>
 
    <mx:List id="list" dataProvider="{arrColl}" textAlign="right" labelField="data" width="100" />
 
    <mx:Button id="button" label="sort items" click="button_click()" />
 
</mx:Application>