ActionScript® 3.0 Reference for the Adobe® Flash® Platform
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mx.collections 

ListCollectionView  - AS3 Flex

Packagemx.collections
Classpublic class ListCollectionView
InheritanceListCollectionView Inheritance Proxy
Implements ICollectionView, IList, IMXMLObject
Subclasses ArrayCollection, XMLListCollection

Language Version: ActionScript 3.0
Product Version: Flex 3
Runtime Versions: Flash Player 9, AIR 1.1

The ListCollectionView class adds the properties and methods of the ICollectionView interface to an object that conforms to the IList interface. As a result, you can pass an object of this class to anything that requires an IList or ICollectionView.

This class also lets you use [ ] array notation to access the getItemAt() and setItemAt() methods. If you use code such as myListCollectionView[index] Flex calls the myListCollectionView object's getItemAt() or setItemAt() method.

MXML SyntaxexpandedHide MXML Syntax

The <mx:ListCollectionView> has the following attributes, which all of its subclasses inherit:

  <mx:ListCollectionView
  Properties
  filterFunction="null"
  list="null"
  sort="null"
  Events
  collectionChange="No default"
  />
  


Public Properties
 PropertyDefined By
  filterFunction : Function
A function that the view will use to eliminate items that do not match the function's criteria.
ListCollectionView
  length : int
[read-only] The number of items in this view.
ListCollectionView
  list : IList
The IList that this collection view wraps.
ListCollectionView
  sort : ISort
The ISort that will be applied to the ICollectionView.
ListCollectionView
Protected Properties
 PropertyDefined By
  localIndex : Array
When the view is sorted or filtered the localIndex property contains an array of items in the sorted or filtered (ordered, reduced) view, in the sorted order.
ListCollectionView
Public Methods
 MethodDefined By
  
The ListCollectionView constructor.
ListCollectionView
  
addAll(addList:IList):void
Adds a list of items to the current list, placing them at the end of the list in the order they are passed.
ListCollectionView
  
addAllAt(addList:IList, index:int):void
Adds a list of items to the current list, placing them at the position index passed in to the function.
ListCollectionView
  
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.
ListCollectionView
  
Adds the specified item to the end of the list.
ListCollectionView
  
addItemAt(item:Object, index:int):void
Adds the item at the specified index.
ListCollectionView
  
Returns whether the view contains the specified object.
ListCollectionView
  
Creates a new IViewCursor that works with this view.
ListCollectionView
  
Prevents changes to the collection itself and items within the collection from being dispatched by the view.
ListCollectionView
  
Dispatches an event into the event flow.
ListCollectionView
  
Enables auto-updating.
ListCollectionView
  
getItemAt(index:int, prefetch:int = 0):Object
Gets the item at the specified index.
ListCollectionView
  
Returns the index of the item if it is in the list such that getItemAt(index) == item.
ListCollectionView
  
Checks whether the EventDispatcher object has any listeners registered for a specific type of event.
ListCollectionView
  
Called automatically by the MXML compiler when the ListCollectionView is created using an MXML tag.
ListCollectionView
  
itemUpdated(item:Object, property:Object = null, oldValue:Object = null, newValue:Object = null):void
Notifies the view that an item has been updated.
ListCollectionView
  
Applies the sort and filter to the view.
ListCollectionView
  
Remove all items from the list.
ListCollectionView
  
removeEventListener(type:String, listener:Function, useCapture:Boolean = false):void
Removes a listener from the EventDispatcher object.
ListCollectionView
  
Removes the item at the specified index and returns it.
ListCollectionView
  
setItemAt(item:Object, index:int):Object
Places the item at the specified index.
ListCollectionView
  
Returns an Array that is populated in the same order as the IList implementation.
ListCollectionView
  
Prints the contents of this view to a string and returns it.
ListCollectionView
  
Checks whether an event listener is registered with this EventDispatcher object or any of its ancestors for the specified event type.
ListCollectionView
Events
 Event Summary Defined By
  Dispatched when the ICollectionView has been updated in some way.ListCollectionView
Property Detail

filterFunction

property
filterFunction:Function

Language Version: ActionScript 3.0
Product Version: Flex 3
Runtime Versions: Flash Player 9, AIR 1.1

A function that the view will use to eliminate items that do not match the function's criteria. A filterFunction is expected to have the following signature:

f(item:Object):Boolean
where the return value is true if the specified item should remain in the view.

If a filter is unsupported, Flex throws an error when accessing this property. You must call refresh() after setting the filterFunction property for the view to update.

Note: The Flex implementations of ICollectionView retrieve all items from a remote location before executing the filter function. If you use paging, apply the filter to the remote collection before you retrieve the data.

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



Implementation
    public function get filterFunction():Function
    public function set filterFunction(value:Function):void

Related API Elements

length

property 
length:int  [read-only]

Language Version: ActionScript 3.0
Product Version: Flex 3
Runtime Versions: Flash Player 9, AIR 1.1

The number of items in this view. 0 means no items, while -1 means that the length is unknown.

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



Implementation
    public function get length():int

list

property 
list:IList

Language Version: ActionScript 3.0
Product Version: Flex 3
Runtime Versions: Flash Player 9, AIR 1.1

The IList that this collection view wraps.

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



Implementation
    public function get list():IList
    public function set list(value:IList):void

localIndex

property 
protected var localIndex:Array

Language Version: ActionScript 3.0
Product Version: Flex 3
Runtime Versions: Flash Player 9, AIR 1.1

When the view is sorted or filtered the localIndex property contains an array of items in the sorted or filtered (ordered, reduced) view, in the sorted order. The ListCollectionView class uses this property to access the items in the view. The localIndex property should never contain anything that is not in the source, but may not have everything in the source. This property is null when there is no sort.

sort

property 
sort:ISort

Language Version: ActionScript 3.0
Product Version: Flex 3
Runtime Versions: Flash Player 9, AIR 1.1

The ISort that will be applied to the ICollectionView. Setting the sort does not automatically refresh the view, so you must call the refresh() method after setting this property. If sort is unsupported an error will be thrown when accessing this property.

Note: The Flex implementations of ICollectionView retrieve all items from a remote location before executing a sort. If you use paging with a sorted list, apply the sort to the remote collection before you retrieve the data.

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



Implementation
    public function get sort():ISort
    public function set sort(value:ISort):void

Related API Elements

Constructor Detail

ListCollectionView

()Constructor
public function ListCollectionView(list:IList = null)

Language Version: ActionScript 3.0
Product Version: Flex 3
Runtime Versions: Flash Player 9, AIR 1.1

The ListCollectionView constructor.

Parameters
list:IList (default = null) — the IList this ListCollectionView is meant to wrap.
Method Detail

addAll

()method
public function addAll(addList:IList):void

Language Version: ActionScript 3.0
Product Version: Flex 3
Runtime Versions: Flash Player 9, AIR 1.1

Adds a list of items to the current list, placing them at the end of the list in the order they are passed.

Parameters

addList:IList — The list of items to add to the current list

addAllAt

()method 
public function addAllAt(addList:IList, index:int):void

Language Version: ActionScript 3.0
Product Version: Flex 3
Runtime Versions: Flash Player 9, AIR 1.1

Adds a list of items to the current list, placing them at the position index passed in to the function. The items are placed at the index location and placed in the order they are recieved.

Parameters

addList:IList — The list of items to add to the current list
 
index:int — The location of the current list to place the new items.

Throws
RangeError — if index is less than 0 or greater than the length of the list.

addEventListener

()method 
public function addEventListener(type:String, listener:Function, useCapture:Boolean = false, priority:int = 0, useWeakReference:Boolean = false):void

Language Version: ActionScript 3.0
Product Version: Flex 3
Runtime Versions: Flash Player 9, AIR 1.1

Registers an event listener object with an EventDispatcher object so that the listener receives notification of an event. You can register event listeners on all nodes in the display list for a specific type of event, phase, and priority.

After you successfully register an event listener, you cannot change its priority through additional calls to addEventListener(). To change a listener's priority, you must first call removeEventListener(). Then you can register the listener again with the new priority level.

After the listener is registered, subsequent calls to addEventListener() with a different value for either type or useCapture result in the creation of a separate listener registration. For example, if you first register a listener with useCapture set to true, it listens only during the capture phase. If you call addEventListener() again using the same listener object, but with useCapture set to false, you have two separate listeners: one that listens during the capture phase, and another that listens during the target and bubbling phases.

You cannot register an event listener for only the target phase or the bubbling phase. Those phases are coupled during registration because bubbling applies only to the ancestors of the target node.

When you no longer need an event listener, remove it by calling EventDispatcher.removeEventListener(); otherwise, memory problems might result. Objects with registered event listeners are not automatically removed from memory because the garbage collector does not remove objects that still have references.

Copying an EventDispatcher instance does not copy the event listeners attached to it. (If your newly created node needs an event listener, you must attach the listener after creating the node.) However, if you move an EventDispatcher instance, the event listeners attached to it move along with it.

If the event listener is being registered on a node while an event is also being processed on this node, the event listener is not triggered during the current phase but may be triggered during a later phase in the event flow, such as the bubbling phase.

If an event listener is removed from a node while an event is being processed on the node, it is still triggered by the current actions. After it is removed, the event listener is never invoked again (unless it is registered again for future processing).

Parameters

type:String — The type of event.
 
listener:Function — The listener function that processes the event. This function must accept an event object as its only parameter and must return nothing, as this example shows:

function(evt:Event):void

The function can have any name.
 
useCapture:Boolean (default = false) — Determines whether the listener works in the capture phase or the target and bubbling phases. If useCapture is set to true, the listener processes the event only during the capture phase and not in the target or bubbling phase. If useCapture is false, the listener processes the event only during the target or bubbling phase. To listen for the event in all three phases, call addEventListener() twice, once with useCapture set to true, then again with useCapture set to false.
 
priority:int (default = 0) — The priority level of the event listener. Priorities are designated by a 32-bit integer. The higher the number, the higher the priority. All listeners with priority n are processed before listeners of priority n-1. If two or more listeners share the same priority, they are processed in the order in which they were added. The default priority is 0.
 
useWeakReference:Boolean (default = false) — Determines whether the reference to the listener is strong or weak. A strong reference (the default) prevents your listener from being garbage-collected. A weak reference does not.

Class-level member functions are not subject to garbage collection, so you can set useWeakReference to true for class-level member functions without subjecting them to garbage collection. If you set useWeakReference to true for a listener that is a nested inner function, the function will be garbge-collected and no longer persistent. If you create references to the inner function (save it in another variable) then it is not garbage-collected and stays persistent.

addItem

()method 
public function addItem(item:Object):void

Language Version: ActionScript 3.0
Product Version: Flex 3
Runtime Versions: Flash Player 9, AIR 1.1

Adds the specified item to the end of the list. Equivalent to addItemAt(item, length).

Parameters

item:Object — The item to add.

addItemAt

()method 
public function addItemAt(item:Object, index:int):void

Language Version: ActionScript 3.0
Product Version: Flex 3
Runtime Versions: Flash Player 9, AIR 1.1

Adds the item at the specified index. The index of any item greater than the index of the added item is increased by one. If the the specified index is less than zero or greater than the length of the list, a RangeError is thrown.

Parameters

item:Object — The item to place at the index.
 
index:int — The index at which to place the item.

contains

()method 
public function contains(item:Object):Boolean

Language Version: ActionScript 3.0
Product Version: Flex 3
Runtime Versions: Flash Player 9, AIR 1.1

Returns whether the view contains the specified object. Unlike the IViewCursor.findxxx methods, this search is succesful only if it finds an item that exactly matches the parameter. If the view has a filter applied to it this method may return false even if the underlying collection does contain the item.

Parameters

item:Object — The object to look for.

Returns
Boolean — true if the ICollectionView, after applying any filter, contains the item; false otherwise.

Related API Elements

createCursor

()method 
public function createCursor():IViewCursor

Language Version: ActionScript 3.0
Product Version: Flex 3
Runtime Versions: Flash Player 9, AIR 1.1

Creates a new IViewCursor that works with this view.

Returns
IViewCursor — A new IViewCursor implementation.

disableAutoUpdate

()method 
public function disableAutoUpdate():void

Language Version: ActionScript 3.0
Product Version: Flex 3
Runtime Versions: Flash Player 9, AIR 1.1

Prevents changes to the collection itself and items within the collection from being dispatched by the view. Also prevents the view from updating the positions of items if the positions change in the collection. The changes will be queued and dispatched appropriately after enableAutoUpdate is called. If more events than updates to a single item occur, the view may end up resetting. The disableAutoUpdate method acts cumulatively; the same number of calls to enableAutoUpdate are required for the view to dispatch events and refresh. Note that disableAutoUpdate only affects the individual view; edits may be detected on an individual basis by other views.

Related API Elements

dispatchEvent

()method 
public function dispatchEvent(event:Event):Boolean

Language Version: ActionScript 3.0
Product Version: Flex 3
Runtime Versions: Flash Player 9, AIR 1.1

Dispatches an event into the event flow. The event target is the EventDispatcher object upon which dispatchEvent() is called.

Parameters

event:Event — The event object dispatched into the event flow.

Returns
Boolean — A value of true unless preventDefault() is called on the event, in which case it returns false.

enableAutoUpdate

()method 
public function enableAutoUpdate():void

Language Version: ActionScript 3.0
Product Version: Flex 3
Runtime Versions: Flash Player 9, AIR 1.1

Enables auto-updating. See disableAutoUpdate for more information.

Related API Elements

getItemAt

()method 
public function getItemAt(index:int, prefetch:int = 0):Object

Language Version: ActionScript 3.0
Product Version: Flex 3
Runtime Versions: Flash Player 9, AIR 1.1

Gets the item at the specified index.

Parameters

index:int — The index in the list from which to retrieve the item.
 
prefetch:int (default = 0) — An int indicating both the direction and number of items to fetch during the request if the item is not local.

Returns
Object — The item at that index, or null if there is none.

getItemIndex

()method 
public function getItemIndex(item:Object):int

Language Version: ActionScript 3.0
Product Version: Flex 3
Runtime Versions: Flash Player 9, AIR 1.1

Returns the index of the item if it is in the list such that getItemAt(index) == item.

Note: unlike IViewCursor.findxxx() methods, The getItemIndex() method cannot take a parameter with only a subset of the fields in the item being serched for; this method always searches for an item that exactly matches the input parameter.

Parameters

item:Object — The item to find.

Returns
int — The index of the item, or -1 if the item is not in the list.

hasEventListener

()method 
public function hasEventListener(type:String):Boolean

Language Version: ActionScript 3.0
Product Version: Flex 3
Runtime Versions: Flash Player 9, AIR 1.1

Checks whether the EventDispatcher object has any listeners registered for a specific type of event. This allows you to determine where an EventDispatcher object has altered handling of an event type in the event flow hierarchy. To determine whether a specific event type will actually trigger an event listener, use IEventDispatcher.willTrigger().

The difference between hasEventListener() and willTrigger() is that hasEventListener() examines only the object to which it belongs, whereas willTrigger() examines the entire event flow for the event specified by the type parameter.

Parameters

type:String — The type of event.

Returns
Boolean — A value of true if a listener of the specified type is registered; false otherwise.

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

Called automatically by the MXML compiler when the ListCollectionView is created using an MXML tag. If you create the ListCollectionView through ActionScript, you must call this method passing in the MXML document and null for the id.

Parameters

document:Object — The MXML document containing this ListCollectionView.
 
id:String — Ignored.

itemUpdated

()method 
public function itemUpdated(item:Object, property:Object = null, oldValue:Object = null, newValue:Object = null):void

Language Version: ActionScript 3.0
Product Version: Flex 3
Runtime Versions: Flash Player 9, AIR 1.1

Notifies the view that an item has been updated. This method is useful if the contents of the view do not implement IPropertyChangeNotifier. If the call to this method includes a property parameter, the view may be able to optimize its notification mechanism. Otherwise it may choose to simply refresh the whole view.

Parameters

item:Object — The item within the view that was updated.
 
property:Object (default = null) — The name of the property that was updated.
 
oldValue:Object (default = null) — The old value of that property. (If property was null, this can be the old value of the item.).
 
newValue:Object (default = null) — The new value of that property. (If property was null, there's no need to specify this as the item is assumed to be the new value.)

Related API Elements

refresh

()method 
public function refresh():Boolean

Language Version: ActionScript 3.0
Product Version: Flex 3
Runtime Versions: Flash Player 9, AIR 1.1

Applies the sort and filter to the view. The ICollectionView does not detect changes to a sort or filter automatically, so you must call the refresh() method to update the view after setting the sort or filterFunction property. If your ICollectionView implementation also implements the IMXMLObject interface, you should to call the refresh() method from your initialized() method.

Returns true if the refresh was successful and false if the sort is not yet complete (e.g., items are still pending). A client of the view should wait for a CollectionEvent event with the CollectionEventKind.REFRESH kind property to ensure that the refresh() operation is complete.

Returns
Booleantrue if the refresh() was complete, false if the refresh() is incomplete.

removeAll

()method 
public function removeAll():void

Language Version: ActionScript 3.0
Product Version: Flex 3
Runtime Versions: Flash Player 9, AIR 1.1

Remove all items from the list.

removeEventListener

()method 
public function removeEventListener(type:String, listener:Function, useCapture:Boolean = false):void

Language Version: ActionScript 3.0
Product Version: Flex 3
Runtime Versions: Flash Player 9, AIR 1.1

Removes a listener from the EventDispatcher object. If there is no matching listener registered with the EventDispatcher object, a call to this method has no effect.

Parameters

type:String — The type of event.
 
listener:Function — The listener object to remove.
 
useCapture:Boolean (default = false) — Specifies whether the listener was registered for the capture phase or the target and bubbling phases. If the listener was registered for both the capture phase and the target and bubbling phases, two calls to removeEventListener() are required to remove both: one call with useCapture set to true, and another call with useCapture set to false.

removeItemAt

()method 
public function removeItemAt(index:int):Object

Language Version: ActionScript 3.0
Product Version: Flex 3
Runtime Versions: Flash Player 9, AIR 1.1

Removes the item at the specified index and returns it. Any items that were after this index are now one index earlier.

Parameters

index:int — The index from which to remove the item.

Returns
Object — The item that was removed.

setItemAt

()method 
public function setItemAt(item:Object, index:int):Object

Language Version: ActionScript 3.0
Product Version: Flex 3
Runtime Versions: Flash Player 9, AIR 1.1

Places the item at the specified index. If an item was already at that index the new item will replace it and it will be returned.

Parameters

item:Object — The new item to be placed at the specified index.
 
index:int — The index at which to place the item.

Returns
Object — The item that was replaced, or null if none.

toArray

()method 
public function toArray():Array

Language Version: ActionScript 3.0
Product Version: Flex 3
Runtime Versions: Flash Player 9, AIR 1.1

Returns an Array that is populated in the same order as the IList implementation. This method can throw an ItemPendingError.

Returns
Array — The array.

toString

()method 
public function toString():String

Language Version: ActionScript 3.0
Product Version: Flex 3
Runtime Versions: Flash Player 9, AIR 1.1

Prints the contents of this view to a string and returns it.

Returns
String — The contents of this view, in string form.

willTrigger

()method 
public function willTrigger(type:String):Boolean

Language Version: ActionScript 3.0
Product Version: Flex 3
Runtime Versions: Flash Player 9, AIR 1.1

Checks whether an event listener is registered with this EventDispatcher object or any of its ancestors for the specified event type. This method returns true if an event listener is triggered during any phase of the event flow when an event of the specified type is dispatched to this EventDispatcher object or any of its descendants.

The difference between hasEventListener() and willTrigger() is that hasEventListener() examines only the object to which it belongs, whereas willTrigger() examines the entire event flow for the event specified by the type parameter.

Parameters

type:String — The type of event.

Returns
Boolean — A value of true if a listener of the specified type will be triggered; false otherwise.
Event Detail

collectionChange

Event
Event Object Type: mx.events.CollectionEvent
property CollectionEvent.type = mx.events.CollectionEvent.COLLECTION_CHANGE

Language Version: ActionScript 3.0
Product Version: Flex 3
Runtime Versions: Flash Player 9, AIR 1.1

Dispatched when the ICollectionView has been updated in some way.

The CollectionEvent.COLLECTION_CHANGE constant defines the value of the type property of the event object for an event that is dispatched when a collection has changed.

The properties of the event object have the following values. Not all properties are meaningful for all kinds of events. See the detailed property descriptions for more information.

PropertyValue
bubblesfalse
cancelablefalse
currentTargetThe 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.
itemsAn Array of objects with information about the items affected by the event. The contents of this field depend on the event kind; for details see the items property
kindThe kind of event. The valid values are defined in the CollectionEventKind class as constants.
locationLocation within the target collection of the item(s) specified in the items property.
oldLocationthe previous location in the collection of the item specified in the items property.
targetThe 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.
typeCollectionEvent.COLLECTION_CHANGE