flex中使用RadioButtonGroup时取出所选项的值的方法

<mx:FormItem label="是否打印：">
<mx:HBox verticalAlign="middle" horizontalGap="15">
<mx:RadioButtonGroup id="dayinID" />
<mx:RadioButton label="不打印" id="noPrint" groupName="dayinID" selected="false"/>
<mx:RadioButton label="打印" id="print" groupName="dayinID"/>
</mx:HBox>
</mx:FormItem>

//是否打印
obj.isPrint = dayinID.selectedValue.toString()=="打印"?'true':'false';