mx.controls.RadioButtonGroup - Adobe® Flex® 4 Language Reference (Flex 4)

Package	mx.controls
Class	public class RadioButtonGroup
Inheritance	RadioButtonGroup EventDispatcher Object
Implements	IMXMLObject

Language Version:

ActionScript 3.0

Product Version:

Flex 3

Runtime Versions:

Flash Player 9, AIR 1.1

Starting with Flex 4.0, Adobe recommends that you use the spark.components.RadioButtonGroup class as an alternative to this class.

The RadioButtonGroup control defines a group of RadioButton controls that act as a single mutually exclusive control; therefore, a user can select only one RadioButton control at a time. While grouping RadioButton instances in a RadioButtonGroup is optional, a group lets you do things like set a single event handler on a group of buttons, rather than on each individual button.

The id property is required when you use the <mx:RadioButtonGroup> tag to define the name of the group.

Notice that the RadioButtonGroup control is a subclass of EventDispatcher, not UIComponent, and implements the IMXMLObject interface. All other Flex visual components are subclasses of UIComponent, which implements the IUIComponent interface. The RadioButtonGroup control has support built into the Flex compiler that allows you to use the RadioButtonGroup control as a child of a Flex container, even though it does not implement IUIComponent. All other container children must implement the IUIComponent interface.

Therefore, if you try to define a visual component as a subclass of EventDispatcher that implements the IMXMLObject interface, you will not be able to use it as the child of a container.

MXML Syntax expanded

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The <mx:RadioButtonGroup> tag inherits all of the tag attributes of its superclass, and adds the following tag attributes:

  <mx:RadioButtonGroup
    Properties
    enabled="true|false"
    id="No default"
    labelPlacement="right|left|top|bottom"
 
    Events
    change="No default"
    itemClick="No default"
  />

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Public Properties

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	Property		Defined By
		constructor : Object A reference to the class object or constructor function for a given object instance.	Object
		enabled : Boolean Determines whether selection is allowed.	RadioButtonGroup
		labelPlacement : String Position of the RadioButton label relative to the RadioButton icon for each control in the group.	RadioButtonGroup
		numRadioButtons : int [read-only] The number of RadioButtons that belong to this RadioButtonGroup.	RadioButtonGroup
		prototype : Object [static] A reference to the prototype object of a class or function object.	Object
		selectedValue : Object The value of the value property of the selected RadioButton control in the group, if this has been set to be something other than null (the default value).	RadioButtonGroup
		selection : RadioButton Contains a reference to the currently selected RadioButton control in the group.	RadioButtonGroup

Public Methods

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	Method		Defined By
		RadioButtonGroup(document:IFlexDisplayObject = null) Constructor.	RadioButtonGroup
		addEventListener(type:String, listener:Function, useCapture:Boolean = false, priority:int = 0, useWeakReference:Boolean = false):void Registers an event listener object with an EventDispatcher object so that the listener receives notification of an event.	EventDispatcher
		dispatchEvent(event:Event):Boolean Dispatches an event into the event flow.	EventDispatcher
		getRadioButtonAt(index:int):RadioButton Returns the RadioButton control at the specified index.	RadioButtonGroup
		hasEventListener(type:String):Boolean Checks whether the EventDispatcher object has any listeners registered for a specific type of event.	EventDispatcher
		hasOwnProperty(name:String):Boolean Indicates whether an object has a specified property defined.	Object
		initialized(document:Object, id:String):void Implementation of the IMXMLObject.initialized() method to support deferred instantiation.	RadioButtonGroup
		isPrototypeOf(theClass:Object):Boolean Indicates whether an instance of the Object class is in the prototype chain of the object specified as the parameter.	Object
		propertyIsEnumerable(name:String):Boolean Indicates whether the specified property exists and is enumerable.	Object
		removeEventListener(type:String, listener:Function, useCapture:Boolean = false):void Removes a listener from the EventDispatcher object.	EventDispatcher
		setPropertyIsEnumerable(name:String, isEnum:Boolean = true):void Sets the availability of a dynamic property for loop operations.	Object
		toLocaleString():String Returns the string representation of this object, formatted according to locale-specific conventions.	Object
		toString():String Returns the string representation of the specified object.	Object
		valueOf():Object Returns the primitive value of the specified object.	Object
		willTrigger(type:String):Boolean Checks whether an event listener is registered with this EventDispatcher object or any of its ancestors for the specified event type.	EventDispatcher

Events

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	Summary	Defined By
activate	[broadcast event] Dispatched when the Flash Player or AIR application gains operating system focus and becomes active.	EventDispatcher
change	Dispatched when the value of the selected RadioButton control in this group changes.	RadioButtonGroup
deactivate	[broadcast event] Dispatched when the Flash Player or AIR application operating loses system focus and is becoming inactive.	EventDispatcher
itemClick	Dispatched when a user selects a RadioButton control in the group.	RadioButtonGroup

Property Detail

enabled

property

enabled:Boolean

Language Version:

ActionScript 3.0

Product Version:

Flex 3

Runtime Versions:

Flash Player 9, AIR 1.1

Determines whether selection is allowed.

The default value is true.

This property can be used as the source for data binding. When this property is modified, it dispatches the enabledChanged event.

Implementation
public function get enabled():Boolean
public function set enabled(value:Boolean):void

labelPlacement

property

labelPlacement:String

Language Version:

ActionScript 3.0

Product Version:

Flex 3

Runtime Versions:

Flash Player 9, AIR 1.1

Position of the RadioButton label relative to the RadioButton icon for each control in the group. You can override this setting for the individual controls.

Valid values in MXML are "right", "left", "bottom", and "top".

In ActionScript, you use the following constants to set this property: ButtonLabelPlacement.RIGHT, ButtonLabelPlacement.LEFT, ButtonLabelPlacement.BOTTOM, and ButtonLabelPlacement.TOP.

The default value is "right".

This property can be used as the source for data binding. When this property is modified, it dispatches the labelPlacementChanged event.

Implementation
public function get labelPlacement():String
public function set labelPlacement(value:String):void

numRadioButtons

property

numRadioButtons:int [read-only]

Language Version:

ActionScript 3.0

Product Version:

Flex 3

Runtime Versions:

Flash Player 9, AIR 1.1

The number of RadioButtons that belong to this RadioButtonGroup.

The default value is "undefined".

This property can be used as the source for data binding. When this property is modified, it dispatches the numRadioButtonsChanged event.

Implementation
public function get numRadioButtons():int

selectedValue

property

selectedValue:Object

Language Version:

ActionScript 3.0

Product Version:

Flex 3

Runtime Versions:

Flash Player 9, AIR 1.1

The value of the value property of the selected RadioButton control in the group, if this has been set to be something other than null (the default value). Otherwise, selectedValue is the value of the label property of the selected RadioButton. If no RadioButton is selected, this property is null.

If you set selectedValue, Flex selects the RadioButton control whose value or label property matches this value.

The default value is null.

This property can be used as the source for data binding. When this property is modified, it dispatches the valueCommit event.

Implementation
public function get selectedValue():Object
public function set selectedValue(value:Object):void

selection

property

selection:RadioButton

Language Version:

ActionScript 3.0

Product Version:

Flex 3

Runtime Versions:

Flash Player 9, AIR 1.1

Contains a reference to the currently selected RadioButton control in the group. You can access the property in ActionScript only; it is not settable in MXML. Setting this property to null deselects the currently selected RadioButton control.

The default value is null.

This property can be used as the source for data binding. When this property is modified, it dispatches the valueCommit event.

Implementation
public function get selection():RadioButton
public function set selection(value:RadioButton):void

Constructor Detail

RadioButtonGroup

()

Constructor

public function RadioButtonGroup(document:IFlexDisplayObject = null)

Language Version:

ActionScript 3.0

Product Version:

Flex 3

Runtime Versions:

Flash Player 9, AIR 1.1

Constructor.

Parameters

document:IFlexDisplayObject (default = null) — In simple cases where a class extends EventDispatcher, the document parameter should not be used.

getRadioButtonAt

()

method

public function getRadioButtonAt(index:int):RadioButton

Language Version:

ActionScript 3.0

Product Version:

Flex 3

Runtime Versions:

Flash Player 9, AIR 1.1

Returns the RadioButton control at the specified index.

Parameters

index:int — The index of the RadioButton control in the RadioButtonGroup control, where the index of the first control is 0.

Returns

RadioButton — The specified RadioButton control.

initialized

()

method

public function initialized(document:Object, id:String):void

Language Version:

ActionScript 3.0

Product Version:

Flex 3

Runtime Versions:

Flash Player 9, AIR 1.1

Implementation of the IMXMLObject.initialized() method to support deferred instantiation.

Parameters

	`document:Object` — The MXML document that created this object.

	`id:String` — The identifier used by document to refer to this object. If the object is a deep property on document, `id` is null.

change

Event

Event Object Type: flash.events.Event
property Event.type = flash.events.Event.CHANGE

Language Version:

ActionScript 3.0

Product Version:

Flex 3

Runtime Versions:

Flash Player 9, AIR 1.1

Dispatched when the value of the selected RadioButton control in this group changes.

The Event.CHANGE constant defines the value of the type property of a change event object.

This event has the following properties:

Property	Value
`bubbles`	`true`
`cancelable`	`false`; there is no default behavior to cancel.
`currentTarget`	The object that is actively processing the Event object with an event listener.
`target`	The object that has had its value modified. The `target` is not always the object in the display list that registered the event listener. Use the `currentTarget` property to access the object in the display list that is currently processing the event.

itemClick

Event

Event Object Type: mx.events.ItemClickEvent
property ItemClickEvent.type = mx.events.ItemClickEvent.ITEM_CLICK

Language Version:

ActionScript 3.0

Product Version:

Flex 3

Runtime Versions:

Flash Player 9, AIR 1.1

Dispatched when a user selects a RadioButton control in the group. You can also set a handler for individual RadioButton controls.

The ItemClickEvent.ITEM_CLICK constant defines the value of the type property of the event object for an itemClick event.

The properties of the event object have the following values:

Property	Value
`bubbles`	false
`cancelable`	false
`currentTarget`	The Object that defines the event listener that handles the event. For example, if you use `myButton.addEventListener()` to register an event listener, myButton is the value of the `currentTarget`.
`index`	The index of the navigation item that was clicked.
`item`	The item in the data provider of the navigation item that was clicked.
`label`	The label of the navigation item that was clicked.
`relatedObject`	The child object that generated the event.
`target`	The Object that dispatched the event; it is not always the Object listening for the event. Use the `currentTarget` property to always access the Object listening for the event.

Examples ( How to use this example )

RadioButtonGroupExample.mxml

<?xml version="1.0" encoding="utf-8"?>
<!-- Simple example to demonstrate Halo RadioButtonGroup control. -->
<s:Application xmlns:fx="http://ns.adobe.com/mxml/2009"
        xmlns:s="library://ns.adobe.com/flex/spark"
        xmlns:mx="library://ns.adobe.com/flex/mx">

    <fx:Script>
        <![CDATA[
            import mx.controls.Alert;
            import  mx.events.ItemClickEvent;
        
            // Event handler function to display the selected button
            // in a Halo Alert control.
            private function handleCard(evt:ItemClickEvent):void {
                switch (evt.currentTarget.selectedValue) {
                    case "AmEx":
                        Alert.show("You selected American Express");
                        break;
                    case "MC":
                        Alert.show("You selected MasterCard");
                        break;
                    case "Visa":
                        Alert.show("You selected Visa");
                        break;
                }
            }
        ]]>
    </fx:Script>

    <fx:Declarations>
        <mx:RadioButtonGroup id="cardtype" itemClick="handleCard(event);"/>
    </fx:Declarations>

    <s:Panel title="Halo RadioButtonGroup Control Example"
            width="75%" height="75%" 
            horizontalCenter="0" verticalCenter="0">
        <s:VGroup left="10" right="10" top="10" bottom="10">
            <s:Label width="100%" color="blue" 
                    text="Select a type of credit card."/>

            <mx:RadioButton groupName="cardtype" id="americanExpress" value="AmEx" 
                    label="American Express" width="150" />
            <mx:RadioButton groupName="cardtype" id="masterCard" value="MC" 
                    label="MasterCard" width="150" />
            <mx:RadioButton groupName="cardtype" id="visa" value="Visa" 
                    label="Visa" width="150" />
        </s:VGroup>
    </s:Panel>

</s:Application>