| Package | mx.collections |
| Class | public class Sort |
| Inheritance | Sort  EventDispatcher Object |
| Implements | ISort |
| Language Version: | ActionScript 3.0 |
| Product Version: | Flex 3 |
| Runtime Versions: | Flash Player 9, AIR 1.1 |
sort property, you must call the view's
refresh() method to apply the sort criteria.
Typically the sort is defined for collections of complex items, that is
collections in which the sort is performed on one or more properties of
the objects in the collection.
The following example shows this use:
var col:ICollectionView = new ArrayCollection();
// In the real world, the collection would have more than one item.
col.addItem({first:"Anders", last:"Dickerson"});
// Create the Sort instance.
var sort:Sort = new Sort();
// Set the sort field; sort on the last name first, first name second.
// Both fields are case-insensitive.
sort.fields = [new SortField("last",true), new SortField("first",true)];
// Assign the Sort object to the view.
col.sort = sort;
// Apply the sort to the collection.
col.refresh();
There are situations in which the collection contains simple items,
like String, Date, Boolean, etc.
In this case, apply the sort to the simple type directly.
When constructing a sort for simple items, use a single sort field,
and specify a null
name (first) parameter
in the SortField object constructor.
For example:
var col:ICollectionView = new ArrayCollection();
col.addItem("California");
col.addItem("Arizona");
var sort:Sort = new Sort();
// There is only one sort field, so use a null
// first parameter.
sort.fields = [new SortField(null, true)];
col.sort = sort;
col.refresh();
The Flex implementations of the ICollectionView interface 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.
By default this Sort class does not provide correct language specific
sorting for strings. For this type of sorting please see the
spark.collections.Sort and
spark.collections.SortField classes.
Show MXML Syntax
Hide MXML SyntaxThe <mx:Sort> tag has the following attributes:
<mx:Sort Properties compareFunction="Internal compare function" fields="null" unique="false | true" />
In case items have inconsistent data types or items have complex data types, the use of the default built-in compare functions is not recommended. Inconsistent sorting results may occur in such cases. To avoid such problem, provide a custom compare function and/or make the item types consistent.
Just like any other AdvancedStyleClient-based classes,
the Sort and SortField classes do not have a
parent-child relationship in terms of event handling. Locale changes in a
Sort instance are not dispatched to its SortField
instances automatically. The only exceptional case is the internal default
SortField instance used when no explicit fields are provided.
In this case, the internal default SortField instance follows
the locale style that the owner Sort instance has.
Default MXML Propertyfields
Related API Elements
| Property | Defined By | ||
|---|---|---|---|
| compareFunction : Function
The method used to compare items when sorting. | Sort | ||
 | constructor : Object
A reference to the class object or constructor function for a given object instance. | Object | |
| fields : Array
An Array of ISortField objects that specifies the fields to compare. | Sort | ||
| unique : Boolean
Indicates if the sort should be unique. | Sort | ||
| Method | Defined By | ||
|---|---|---|---|
Sort()
Constructor. | Sort | ||
| 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 | |
|
Dispatches an event into the event flow. | EventDispatcher | |
findItem(items:Array, values:Object, mode:String, returnInsertionIndex:Boolean = false, compareFunction:Function = null):int
Finds the specified object within the specified array (or the insertion
point if asked for), returning the index if found or -1 if not. | Sort | ||
|
Checks whether the EventDispatcher object has any listeners registered for a specific type
of event. | EventDispatcher | |
|
Indicates whether an object has a specified property defined. | Object | |
|
Indicates whether an instance of the Object class is in the prototype chain of the object specified
as the parameter. | Object | |
Return whether the specified property is used to control the sort. | Sort | ||
|
Indicates whether the specified property exists and is enumerable. | Object | |
|
Removes a listener from the EventDispatcher object. | EventDispatcher | |
Goes through the fields array and calls
reverse() on each of the ISortField objects in
the array. | Sort | ||
|
Sets the availability of a dynamic property for loop operations. | Object | |
Apply the current sort to the specified array (not a copy). | Sort | ||
|
Returns the string representation of this object, formatted according to locale-specific conventions. | Object | |
|
Returns the string representation of the specified object. | Object | |
|
Returns the primitive value of the specified object. | Object | |
|
Checks whether an event listener is registered with this EventDispatcher object or any of
its ancestors for the specified event type. | EventDispatcher | |
| Constant | Defined By | ||
|---|---|---|---|
| ANY_INDEX_MODE : String = "any" [static]
When executing a find return the index any matching item. | Sort | ||
| FIRST_INDEX_MODE : String = "first" [static]
When executing a find return the index for the first matching item. | Sort | ||
| LAST_INDEX_MODE : String = "last" [static]
When executing a find return the index for the last matching item. | Sort | ||
compareFunction | property |
compareFunction:Function| Language Version: | ActionScript 3.0 |
| Product Version: | Flex 3 |
| Runtime Versions: | Flash Player 9, AIR 1.1 |
The method used to compare items when sorting.
If you specify this property, Flex ignores any
compareFunction properties that you specify in the
ISortField objects that you use in this class.
The compare function must have the following signature:
function [name](a:Object, b:Object, fields:Array = null):int
This function must return the following value:
- -1, if the
Object ashould appear before theObject bin the sorted sequence - 0, if the
Object aequals theObject b - 1, if the
Object ashould appear after theObject bin the sorted sequence
To return to the internal comparision function, set this value to
null.
The fields array specifies the object fields
to compare.
Typically the algorithm will compare properties until the field list is
exhausted or a non-zero value can be returned.
For example:
function myCompare(a:Object, b:Object, fields:Array = null):int
{
var result:int = 0;
var i:int = 0;
var propList:Array = fields ? fields : internalPropList;
var len:int = propList.length;
var propName:String;
while (result == 0 && (i < len))
{
propName = propList[i];
result = compareValues(a[propName], b[propName]);
i++;
}
return result;
}
function compareValues(a:Object, b:Object):int
{
if (a == null && b == null)
return 0;
if (a == null)
return 1;
if (b == null)
return -1;
if (a < b)
return -1;
if (a > b)
return 1;
return 0;
}
The default value is an internal compare function that can perform a string, numeric, or date comparison in ascending or descending order. Specify your own function only if you need a need a custom comparison algorithm. This is normally only the case if a calculated field is used in a display.
Alternatively you can specify separate compare functions for each
sort field by using the ISortField class
compareFunction property; This way you can use the default
comparison for some fields and a custom comparison for others.
Implementation
public function get compareFunction():Function public function set compareFunction(value:Function):voidfields | property |
fields:Array| Language Version: | ActionScript 3.0 |
| Product Version: | Flex 3 |
| Runtime Versions: | Flash Player 9, AIR 1.1 |
An Array of ISortField objects that specifies the fields to compare.
The order of the ISortField objects in the array determines
field priority order when sorting.
The default sort comparator checks the sort fields in array
order until it determinines a sort order for the two
fields being compared.
The default value is null.
This property can be used as the source for data binding. When this property is modified, it dispatches the fieldsChanged event.
Implementation
public function get fields():Array public function set fields(value:Array):voidRelated API Elements
unique | property |
unique:Boolean| Language Version: | ActionScript 3.0 |
| Product Version: | Flex 3 |
| Runtime Versions: | Flash Player 9, AIR 1.1 |
Indicates if the sort should be unique.
Unique sorts fail if any value or combined value specified by the
fields listed in the fields property result in an indeterminate or
non-unique sort order; that is, if two or more items have identical
sort field values. An error is thrown if the sort is not unique.
The sorting logic uses this unique property value only if sort
field(s) are specified explicitly. If no sort fields are specified
explicitly, no error is thrown even when there are identical value
elements.
The default value is false.
Implementation
public function get unique():Boolean public function set unique(value:Boolean):voidSort | () | Constructor |
public function Sort()| Language Version: | ActionScript 3.0 |
| Product Version: | Flex 3 |
| Runtime Versions: | Flash Player 9, AIR 1.1 |
Constructor.
Creates a new Sort with no fields set and no custom comparator.
findItem | () | method |
public function findItem(items:Array, values:Object, mode:String, returnInsertionIndex:Boolean = false, compareFunction:Function = null):int| Language Version: | ActionScript 3.0 |
| Product Version: | Flex 3 |
| Runtime Versions: | Flash Player 9, AIR 1.1 |
Finds the specified object within the specified array (or the insertion
point if asked for), returning the index if found or -1 if not.
The ListCollectionView class findxxx()
methods use this method to find the requested item; as a general rule,
it is easier to use these functions, and not findItem()
to find data in ListCollectionView-based objects.
You call the findItem() method directly when writing a
class that supports sorting, such as a new ICollectionView
implementation.
The input items array need to be sorted before calling this function.
Otherwise this function will not be able to find the specified value
properly.
Parameters
items:Array — the Array within which to search.
| |||||||
values:Object — Object containing the properties to look for (or
the object to search for, itself).
The object must consist of field name/value pairs, where
the field names are names of fields specified by the
fields property, in the same order they
are used in that property.
You do not have to specify all of the fields from the
fields property, but you
cannot skip any in the order.
Therefore, if the fields
properity lists three fields, you can specify its first
and second fields in this parameter, but you cannot
specify only the first and third fields.
| |||||||
mode:String — String containing the type of find to perform.
Valid values are:
| |||||||
returnInsertionIndex:Boolean (default = false)values parameter,
and this parameter is true the
findItem()
method returns the insertion point for the values,
that is the point in the sorted order where you
should insert the item.
| |||||||
compareFunction:Function (default = null)null value,
findItem() function uses the
compare function determined by the ISort
instance's compareFunction property,
passing in the array of fields determined
by the values object and the current
SortFields.
If you provide a non-null value, findItem()
function uses it as the compare function.
The signature of the function passed as
compareFunction must be as follows:
function myCompareFunction(a:Object, b:Object):int.
Note that there is no third argument unlike the
compare function for ISort.compareFunction()
property.
|
int — int The index in the array of the found item.
If the returnInsertionIndex parameter is
false and the item is not found, returns -1.
If the returnInsertionIndex parameter is
true and the item is not found, returns
the index of the point in the sorted array where the
values would be inserted.
|
propertyAffectsSort | () | method |
public function propertyAffectsSort(property:String):Boolean| Language Version: | ActionScript 3.0 |
| Product Version: | Flex 3 |
| Runtime Versions: | Flash Player 9, AIR 1.1 |
Return whether the specified property is used to control the sort.
The function cannot determine a definitive answer if the sort uses a
custom comparator; it always returns true in this case.
Parameters
property:String — The name of the field that to test.
|
Boolean — Whether the property value might affect the sort outcome.
If the sort uses the default compareFunction, returns
true if the
property parameter specifies a sort field.
If the sort or any ISortField uses a custom comparator,
there's no way to know, so return true.
|
reverse | () | method |
public function reverse():void| Language Version: | ActionScript 3.0 |
| Product Version: | Flex 3 |
| Runtime Versions: | Flash Player 9, AIR 1.1 |
Goes through the fields array and calls
reverse() on each of the ISortField objects in
the array. If the field was descending now it is ascending,
and vice versa.
Note: an ICollectionView does not automatically
update when the objects in the fields array are modified;
call its refresh() method to update the view.
sort | () | method |
public function sort(items:Array):void| Language Version: | ActionScript 3.0 |
| Product Version: | Flex 3 |
| Runtime Versions: | Flash Player 9, AIR 1.1 |
Apply the current sort to the specified array (not a copy).
To prevent the array from being modified, create a copy
use the copy in the items parameter.
Flex ICollectionView implementations call the
sort method automatically and ensure that the sort is
performed on a copy of the underlying data.
Parameters
items:Array — Array of items to sort.
|
ANY_INDEX_MODE | Constant |
public static const ANY_INDEX_MODE:String = "any"| Language Version: | ActionScript 3.0 |
| Product Version: | Flex 3 |
| Runtime Versions: | Flash Player 9, AIR 1.1 |
When executing a find return the index any matching item.
FIRST_INDEX_MODE | Constant |
public static const FIRST_INDEX_MODE:String = "first"| Language Version: | ActionScript 3.0 |
| Product Version: | Flex 3 |
| Runtime Versions: | Flash Player 9, AIR 1.1 |
When executing a find return the index for the first matching item.
LAST_INDEX_MODE | Constant |
public static const LAST_INDEX_MODE:String = "last"| Language Version: | ActionScript 3.0 |
| Product Version: | Flex 3 |
| Runtime Versions: | Flash Player 9, AIR 1.1 |
When executing a find return the index for the last matching item.
Mon Apr 10 2017, 12:28 PM -07:00