import mx.collections.ArrayCollection; 
import flash.filesystem.File;

//declare array collection 'listfiles' dataprovider for the list//			
private var listfiles:ArrayCollection=new ArrayCollection();

private function listdesktopfiles():void{

//point the file object 'desktop' to the desktop path//			

var desktop:File = File.desktopDirectory;
/* var desktop:File = File.desktopDirectory.resolvePath("Adobe AIR"); 
will direct the path to the subdirectory 'Adobe AIR' available on the desktop */

//getDirectoryListing() returns array of file objects from the file object pointer, desktop in this case//
var getfiles:Array = desktop.getDirectoryListing();

//Push all thi values to the Arraycollection to be diaplayed in the list//
for (var i:int = 0; i < getfiles.length; i++) { 			  	 			  
	listfiles.addItemAt((getfiles[i].nativePath), i);   
	}
}

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Display all files in a folder

Get all files from a folder

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ActionScript 3