spark.components.RadioButtonGroup - Adobe® Flex® 4 Language Reference (Flex 4)

Package	spark.components
Class	public class RadioButtonGroup
Inheritance	RadioButtonGroup EventDispatcher Object
Implements	IMXMLObject

Language Version:

ActionScript 3.0

Product Version:

Flex 4

Runtime Versions:

Flash Player 10, AIR 1.5

The RadioButtonGroup component defines a group of RadioButton components that act as a single mutually exclusive component; therefore, a user can select only one RadioButton component at a time. The id property is required when you use the <s:RadioButtonGroup> tag to define the group name. Any <s:RadioButton> component added to this group will have this group name.

Notice that the RadioButtonGroup component is a subclass of EventDispatcher, not UIComponent, and implements the IMXMLObject interface. All other Flex visual components implement the IVisualElement interface. The RadioButtonGroup component declaration must be contained within the <Declarations> tag since it is not assignable to IVisualElement.

MXML Syntax expanded

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

  <s:RadioButtonGroup
    Properties
    enabled="true"
    selectedValue="null"
    selection="null"
 
    Events
    change="No default"
    itemClick="No default"
    valueCommit="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
		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 property of the selected RadioButton component in the group, if it has been set, otherwise, the label property of the selected RadioButton.	RadioButtonGroup
		selection : RadioButton Contains a reference to the currently selected RadioButton component 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 component 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 component 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 component in the group.	RadioButtonGroup
valueCommit	Dispatched when values are changed programmatically or by user interaction.	RadioButtonGroup

Property Detail

enabled

property

enabled:Boolean

Language Version:

ActionScript 3.0

Product Version:

Flex 4

Runtime Versions:

Flash Player 10, AIR 1.5

Determines whether selection is allowed. Note that the value returned only reflects the value that was explicitly set on the RadioButtonGroup and does not reflect any values explicitly set on the individual RadioButtons.

The default value is true.

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

numRadioButtons

property

numRadioButtons:int [read-only]

Language Version:

ActionScript 3.0

Product Version:

Flex 4

Runtime Versions:

Flash Player 10, AIR 1.5

The number of RadioButtons that belong to this RadioButtonGroup.

The default value is "0".

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 4

Runtime Versions:

Flash Player 10, AIR 1.5

The value property of the selected RadioButton component in the group, if it has been set, otherwise, the label property of the selected RadioButton. If no RadioButton is selected, this property is null.

If you set selectedValue, Flex selects the first RadioButton component 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 4

Runtime Versions:

Flash Player 10, AIR 1.5

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

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 4

Runtime Versions:

Flash Player 10, AIR 1.5

Constructor.

Parameters

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

See also

flash.events.EventDispatcher

Method Detail

getRadioButtonAt

()

method

public function getRadioButtonAt(index:int):RadioButton

Language Version:

ActionScript 3.0

Product Version:

Flex 4

Runtime Versions:

Flash Player 10, AIR 1.5

Returns the RadioButton component at the specified index.

Parameters

index:int — The 0-based index of the RadioButton in the RadioButtonGroup.

Returns

RadioButton — The specified RadioButton component if index is between 0 and numRadioButtons - 1. Returns null if the index is invalid.

See also

numRadioButtons

initialized

()

method

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

Language Version:

ActionScript 3.0

Product Version:

Flex 4

Runtime Versions:

Flash Player 10, AIR 1.5

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.

See also

mx.core.IMXMLObject

Event Detail

change

Event

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

Language Version:

ActionScript 3.0

Product Version:

Flex 4

Runtime Versions:

Flash Player 10, AIR 1.5

Dispatched when the value of the selected RadioButton component 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 4

Runtime Versions:

Flash Player 10, AIR 1.5

Dispatched when a user selects a RadioButton component in the group. You can also set a handler for individual RadioButton components. This event is dispatched only when the user interacts with the radio buttons by using the mouse.

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.

valueCommit

Event

Event Object Type: mx.events.FlexEvent
property FlexEvent.type = mx.events.FlexEvent.VALUE_COMMIT

Language Version:

ActionScript 3.0

Product Version:

Flex 3

Runtime Versions:

Flash Player 9, AIR 1.1

Dispatched when values are changed programmatically or by user interaction.

Because a programmatic change triggers this event, make sure that any valueCommit event handler does not change a value that causes another valueCommit event. For example, do not change theselectedValue property or selection property in a valueCommit event handler.

The FlexEvent.VALUE_COMMIT constant defines the value of the type property of the event object for a valueCommit 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`.
`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"?>
<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;
            
            private function handlePayment(event:ItemClickEvent):void {
                if (event.currentTarget.selectedValue == "check") {
                    Alert.show("You opted to pay by check."); 
                } else if (event.currentTarget.selectedValue == "credit") {
                    Alert.show("You opted to pay by credit card.");
                }
            }
        ]]>
    </fx:Script>
    
    <fx:Declarations>
        <s:RadioButtonGroup id="paymentType" itemClick="handlePayment(event);"/>
    </fx:Declarations>
    <s:VGroup paddingLeft="10" paddingTop="10">
        <s:RadioButton groupName="paymentType" 
                       id="payCheck" 
                       value="check" 
                       label="Pay by check" 
                       width="150"/>
        <s:RadioButton groupName="paymentType" 
                       id="payCredit" 
                       value="credit" 
                       label="Pay by credit card" 
                       width="150"/>
    </s:VGroup>
</s:Application>