how to compare two array collection using action script - actionscript-3

Question

how to compare two arraycollection
collectionArray1 = ({first: 'Dave', last: 'Matthews'},...........n values
collectionArray = ({first: 'Dave', last: 'Matthews'},...........n values
how to compare..if equal just alert nochange if not alert chaged

Answer 1

If you just want to know if they are different from each other, meaning by length, order or individual items, you can do the following, which first checks to see if the lengths are different, then checks to see if the individual elements are different. This isn't terribly reusable, it's left as an exercise for the reader to split this apart into cleaner chunks :)
public function foo(coll1:ArrayCollection, coll2:ArrayCollection):void {
if (coll1.length == coll2.length) {
for (var i:int = 0; i < coll1.length; i++) {
if (coll1[i].first != coll2[i].first || coll1[i].last != coll2[i].last) {
Alert.show("Different");
return;
}
}
}
Alert.show("Same");
}

Answer 2

/* elements need to implement valueOf
public function valueOf():Object{}
*/
public static function equalsByValueOf(
first:ArrayCollection,
seconde:ArrayCollection):Boolean{
if((first==null) != (seconde==null) ){
return false;
}else if(!first && !seconde){
return false;
}
if(first.length!=seconde.length){
return false;
}
var commonLength:int = first.length;
var dictionary:Dictionary = new Dictionary();
for(var i:int=0;i<commonLength;i++){
var item1:Object = first.getItemAt(i);
var item2:Object = seconde.getItemAt(i);
dictionary[item1.valueOf()]=i;
dictionary[item2.valueOf()]=i;
}
var count:int = 0;
for (var key:Object in dictionary)
{
count++;
}
return count==commonLength;
}
/* valueOf sample
* something like javaObject.hashCode()
* use non changing fields(recommended)
*/
public function valueOf():Object{
return "_"+nonChangeField1+"_"+nonChangeField2+"...";
}

Answer 3

I was going to say this.
if(collectionArray === collectionArray1)
But that wont work (not triple = signs). As === is used to see classes.
I would write a function called check if object exists in array.
Create an array to hold elements that are not found. eg notFound
in Collection1 go through all the element and see if they exist in Collection2, if an element does not exist, add it to the notFound array. Use the function your created in step1
Now check Collection2, if an element is not found add it to the notFound array.
There is no 5.

Answer 4

Dude, use the mx.utils.ObjectUtil... the creators of actionscript have already thought about this.
ObjectUtil.compare(collection1, collection2) == 0;