Sorting date columns in a DataGrid

<?xml version="1.0" encoding="utf-8"?>
<!-- http://blog.flexexamples.com/2007/08/12/sorting-date-columns-in-a-datagrid/ -->
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"
        layout="vertical"
        verticalAlign="middle"
        backgroundColor="white">
 
    <mx:Script>
        <![CDATA[
            import mx.utils.ObjectUtil;
 
            private function date_sortCompareFunc(itemA:Object, itemB:Object):int {
                /* Date.parse() returns an int, but
                   ObjectUtil.dateCompare() expects two
                   Date objects, so convert String to
                   int to Date. */
                var dateA:Date = new Date(Date.parse(itemA.dob));
                var dateB:Date = new Date(Date.parse(itemB.dob));
                return ObjectUtil.dateCompare(dateA, dateB);
            }
 
            private function date_dataTipFunc(item:Object):String {
                return dateFormatter.format(item.dob);
            }
        ]]>
    </mx:Script>
 
    <mx:ArrayCollection id="arrColl">
        <mx:source>
            <mx:Array>
                <mx:Object name="User A" dob="04/14/1980" />
                <mx:Object name="User B" dob="01/02/1975" />
                <mx:Object name="User C" dob="12/30/1977" />
                <mx:Object name="User D" dob="10/27/1968" />
            </mx:Array>
        </mx:source>
    </mx:ArrayCollection>
 
    <mx:DateFormatter id="dateFormatter" formatString="MMMM D, YYYY" />
 
    <mx:DataGrid id="dataGrid" dataProvider="{arrColl}">
        <mx:columns>
            <mx:DataGridColumn dataField="name"
                    headerText="Name:" />
 
            <mx:DataGridColumn dataField="dob"
                    headerText="Date of birth:"
                    sortCompareFunction="date_sortCompareFunc"
                    showDataTips="true"
                    dataTipFunction="date_dataTipFunc" />
        </mx:columns>
    </mx:DataGrid>
 
</mx:Application>