检测RadioButtonGroup控件中的哪个RadioButton被选中.

RadioButtonGroup控件的itemClick事件。
示例：

代码：

<?xml version="1.0" encoding="utf-8"?>
<!-- http://blog.flexexamples.com/2008/06/21/detecting-when-a-radiobutton-has-been-clicked-in-a-radiobuttongroup-in-flex/ -->
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"
        layout="vertical"
        verticalAlign="middle"
        backgroundColor="white">

    <mx:Script>
        <![CDATA[
            import mx.events.ItemClickEvent;

            private function radioGroup_itemClick(evt:ItemClickEvent):void {
                var now:String = new Date().toTimeString();
                lbl.text = evt.label + " (" + now + ")";
            }
        ]]>
    </mx:Script>

    <mx:ApplicationControlBar dock="true">
        <mx:Label id="lbl" fontWeight="bold" />
    </mx:ApplicationControlBar>

    <mx:RadioButtonGroup id="radioGroup"
            itemClick="radioGroup_itemClick(event);" />

    <mx:VBox>
        <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:VBox>

</mx:Application>

也可以通过AS实现：

<?xml version="1.0" encoding="utf-8"?>
<!-- http://blog.flexexamples.com/2008/06/21/detecting-when-a-radiobutton-has-been-clicked-in-a-radiobuttongroup-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.containers.VBox;
            import mx.containers.ApplicationControlBar;
            import mx.controls.Label;
            import mx.controls.RadioButton;
            import mx.controls.RadioButtonGroup;
            import mx.events.ItemClickEvent;

            private var lbl:Label;
            private var radioGroup:RadioButtonGroup;
            private var radioButton1:RadioButton;
            private var radioButton2:RadioButton;
            private var radioButton3:RadioButton;
            private var radioButton4:RadioButton;
            private var radioButton5:RadioButton;

            private function init():void {
                lbl = new Label();
                lbl.setStyle("fontWeight", "bold");

                var appControlBar:ApplicationControlBar;
                appControlBar = new ApplicationControlBar();
                appControlBar.dock = true;
                appControlBar.addChild(lbl);
                Application.application.addChildAt(appControlBar, 0);

                radioGroup = new RadioButtonGroup();
                radioGroup.addEventListener(ItemClickEvent.ITEM_CLICK,
                            radioGroup_itemClick);

                radioButton1 = new RadioButton();
                radioButton1.label = "Red";
                radioButton1.group = radioGroup;

                radioButton2 = new RadioButton();
                radioButton2.label = "Orange";
                radioButton2.group = radioGroup;

                radioButton3 = new RadioButton();
                radioButton3.label = "Yellow";
                radioButton3.group = radioGroup;

                radioButton4 = new RadioButton();
                radioButton4.label = "Green";
                radioButton4.group = radioGroup;

                radioButton5 = new RadioButton();
                radioButton5.label = "Blue";
                radioButton5.group = radioGroup;

                var vBox:VBox = new VBox();
                vBox.addChild(radioButton1);
                vBox.addChild(radioButton2);
                vBox.addChild(radioButton3);
                vBox.addChild(radioButton4);
                vBox.addChild(radioButton5);
                addChild(vBox);
            }

            private function radioGroup_itemClick(evt:ItemClickEvent):void {
                var now:String = new Date().toTimeString();
                lbl.text = evt.label + " (" + now + ")";
            }
        ]]>
    </mx:Script>

</mx:Application>