Flex Newbie XMLList question - Sorting XML and XMLList

问题

Is it possible to sort an XMLList? All the examples I can find on it create a new XMLListCollection like this:

MyXMLListCol = new XMLListCollection(MyXMLList);

I don't think the XMLListCollection in this case has any reference to the XMLList so sorting it would leave my XMLList unsorted, is this correct?

How can I sort the XMLList directly?

Thanks ~Mike

回答1:

So I finally got my search terms altered enough I actually churned up an answer to this. Using the technique I got from here: http://freerpad.blogspot.com/2007/07/more-hierarchical-sorting-e4x-xml-for.html

I was able to come up with this:

public function sortXMLListByAttribute(parentNode:XML,xList:XMLList,attr:String):void{
//attr values must be ints
var xListItems:int = xList.length();
if(xListItems !=0){
    var sortingArray:Array = new Array();
    var sortAttr:Number = new Number();
    for each (var item:XML in xList){
        sortAttr = Number(item.attribute(attr));
        if(sortingArray.indexOf(sortAttr)==-1){
            sortingArray.push(sortAttr);
        }
        //piggy back the removal, just have to remove all of one localName without touching items of other localNames
        delete parentNode.child(item.localName())[0];
    }
    if( sortingArray.length > 1 ) {
        sortingArray.sort(Array.NUMERIC);
    }

    var sortedList:XMLList = new XMLList();
    for each(var sortedAttr:Number in sortingArray){
        for each (var item2:XML in xList){
            var tempVar:Number = Number(item2.attribute(attr));
            if(tempVar == sortedAttr){
                sortedList += item2
            }
        }
    }
    for each(var item3:XML in sortedList){
        parentNode.appendChild(item3);
    }
}
}

Works pretty fast and keeps my original XML variable updated. I know I may be reinventing the wheel just to not use an XMLListCollection, but I think the ability to sort XML and XMLLists can be pretty important

回答2:

While there is no native equivalent to the Array.sortOn function, it is trivial enough to implement your own sorting algorithm:

// Bubble sort.

// always initialize variables -- it save memory.
var ordered:Boolean = false;
var l:int = xmlList.length();
var i:int = 0;
var curr:XML = null;
var plus:XML = null;
while( !ordered )
{
    // Assume that the order is correct
    ordered = true;
    for( i = 0; i < l; i++ )
    {
        curr = xmlList[ i ];
        plus = xmlList[ i + 1 ];    

        // If the order is incorrect, swap and set ordered to false.
        if( Number( curr.@order ) < Number( plus.@order ) )
        {
            xmlList[ i ]     = plus;
            xmlList[ i + 1 ] = curr;
            ordered = false;
        }
    }
}

but, realistically, it is far easier and less buggy to use XMLListCollection. Further, if someone else is reading your code, they will find it easier to understand. Please do yourself a favor and avoid re-inventing the wheel on this.

来源：https://stackoverflow.com/questions/1869964/flex-newbie-xmllist-question-sorting-xml-and-xmllist

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apache-flex

flex3