ListCollectionView

Package	mx.collections
Class	public class ListCollectionView
Inheritance	ListCollectionView 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 Syntax expanded

Hide 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

	Property		Defined 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

	Property		Defined 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

	Method		Defined By
		ListCollectionView(list:IList = null) 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
		addItem(item:Object):void 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
		contains(item:Object):Boolean Returns whether the view contains the specified object.	ListCollectionView
		createCursor():IViewCursor Creates a new IViewCursor that works with this view.	ListCollectionView
		disableAutoUpdate():void Prevents changes to the collection itself and items within the collection from being dispatched by the view.	ListCollectionView
		dispatchEvent(event:Event):Boolean Dispatches an event into the event flow.	ListCollectionView
		enableAutoUpdate():void Enables auto-updating.	ListCollectionView
		getItemAt(index:int, prefetch:int = 0):Object Gets the item at the specified index.	ListCollectionView
		getItemIndex(item:Object):int Returns the index of the item if it is in the list such that getItemAt(index) == item.	ListCollectionView
		hasEventListener(type:String):Boolean Checks whether the EventDispatcher object has any listeners registered for a specific type of event.	ListCollectionView
		initialized(document:Object, id:String):void 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
		refresh():Boolean Applies the sort and filter to the view.	ListCollectionView
		removeAll():void Remove all items from the list.	ListCollectionView
		removeEventListener(type:String, listener:Function, useCapture:Boolean = false):void Removes a listener from the EventDispatcher object.	ListCollectionView
		removeItemAt(index:int):Object 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
		toArray():Array Returns an Array that is populated in the same order as the IList implementation.	ListCollectionView
		toString():String Prints the contents of this view to a string and returns it.	ListCollectionView
		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.	ListCollectionView

Events

Click for more information on events

	Event		Summary	Defined By
		collectionChange	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

refresh()

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

refresh()

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

enableAutoUpdate()
mx.events.CollectionEvent

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

mx.collections.ICollectionView.enableAutoUpdate()
mx.events.CollectionEvent

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

mx.collections.ICollectionView.disableAutoUpdate()

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

mx.events.CollectionEvent
mx.core.IPropertyChangeNotifier
mx.events.PropertyChangeEvent

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

Boolean — true 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.

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.

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`.
`items`	An 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
`kind`	The kind of event. The valid values are defined in the CollectionEventKind class as constants.
`location`	Location within the target collection of the item(s) specified in the `items` property.
`oldLocation`	the previous location in the collection of the item specified in the `items` property.
`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.
`type`	CollectionEvent.COLLECTION_CHANGE

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ListCollectionView - AS3 Flex

Classes x

filterFunction

length

list

localIndex

sort

ListCollectionView

addAll

addAllAt

addEventListener

addItem

addItemAt

contains

createCursor

disableAutoUpdate

dispatchEvent

enableAutoUpdate

getItemAt

getItemIndex

hasEventListener

initialized

itemUpdated

refresh

removeAll

removeEventListener

removeItemAt

setItemAt

toArray

toString

willTrigger

collectionChange