The following example shows how you can detect when the number of RadioButton objects changes in a RadioButtonGroup in Flex by listening for the numRadioButtonsChanged event.
Full code after the jump.
<?xml version="1.0" encoding="utf-8"?>
<!-- http://blog.flexexamples.com/2008/11/10/detecting-when-the-number-of-radio-buttons-changes-in-a-radio-button-group-in-flex/ -->
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"
layout="vertical"
verticalAlign="middle"
backgroundColor="white"
initialize="init();">
<mx:Script>
<![CDATA[
import mx.controls.Alert;
private function init():void {
radioGroup.addEventListener("numRadioButtonsChanged", radioGroup_numRadioButtonsChanged);
}
private function radioGroup_numRadioButtonsChanged(evt:Event):void {
var rb:RadioButton = radioGroup.getRadioButtonAt(radioGroup.numRadioButtons-1);
var alert:Alert = Alert.show(evt.toString(), "label:" + rb.label);
alert.status = "numRadioButtons:" + radioGroup.numRadioButtons;
}
]]>
</mx:Script>
<mx:RadioButtonGroup id="radioGroup" />
<mx:HBox>
<mx:RadioButton id="radioButton1" label="Red" group="{radioGroup}" />
<mx:RadioButton id="radioButton2" label="Orange" group="{radioGroup}" />
<mx:RadioButton id="radioButton3" label="Yellow" group="{radioGroup}" />
<mx:RadioButton id="radioButton4" label="Green" group="{radioGroup}" />
<mx:RadioButton id="radioButton5" label="Blue" group="{radioGroup}" />
</mx:HBox>
</mx:Application>
