Getting data from custom classes (an OOP question)

How can I get some var / data from a custom classes?

The XML class

package classes
{
    import flash.net.URLLoader;
    import flash.net.URLRequest;
    import flash.events.Event;
    import flash.display.MovieClip;

    public class videoData extends MovieClip
    {   
       private var myXML:XML;
       private var myXMList:XMLList;

       public function videoData()
       {
          var myXMLLoader:URLLoader = new URLLoader();
          myXMLLoader.load(new URLRequest("playlist.xml"));
          myXMLLoader.addEventListener(Event.COMPLETE, processXML);
       }

       private function processXML(e:Event):void
       {
          myXML = new XML(e.target.data);
          myXMList = new XMLList(myXML.children());
       }

       public function getXML()
       {
          return myXML;
       }
    }开发者_StackOverflow
}

The class that is calling the XML

package classes
{
    import flash.display.MovieClip;
    import flash.events.MouseEvent;
    import classes.videoData;

    public class playList extends MovieClip
    {
       private var vData:videoData = new videoData();

       public function playList()
       {
          trace(vData.getXML())
       }
    }
}

I would setup an event listener in 'playList' and dispatch an Event from 'videoData' once the XML has finished loading. That way you know when it's finished loading without using ENTER_FRAME (which will use alot more CPU as its checking every frame).

package classes
{
    import flash.events.*;
    import flash.display.MovieClip;
    import classes.VideoData;

    public class PlayList extends MovieClip
    {
       private var vData:VideoData;

       public function PlayList()
       {
           vData = new VideoData();
           vData.addEventListener(Event.COMPLETE, onXMLCompleteHandler);
       }

       private function onXMLCompleteHandler(e:Event):void
       {
           vData.removeEventListener(Event.COMPLETE, onXMLCompleteHandler);
           trace(vData.getXML());
       }
    }
}

package classes
{
    import flash.net.URLLoader;
    import flash.net.URLRequest;
    import flash.events.Event;
    import flash.display.MovieClip;

    public class VideoData extends MovieClip
    {   
       private var myXML:XML;
       private var myXMList:XMLList;
       private var myXMLLoader:URLLoader;

       public function VideoData()
       {
          myXMLLoader = new URLLoader();
          myXMLLoader.load(new URLRequest("playlist.xml"));
          myXMLLoader.addEventListener(Event.COMPLETE, processXML);
       }

       private function processXML(e:Event):void
       {
           myXMLLoader.removeEventListener(Event.COMPLETE, processXML);
           myXML = new XML(e.target.data);
           myXMList = new XMLList(myXML.children());
           dispatchEvent(e);
       }

       public function getXML():XML
       {
           return myXML;
       }
    }
}

You should also ALWAYS capitalise your class names 'VideoData' not 'videoData'

You will need for the XML data to have been received before getting a value. Add a private Boolean _xmlLoaded in your videoData class , set it to true in the processXML method.

Create a getter

public function get xmlLoaded():Boolean
{
   return _xmlLoaded;
}

Now you can do this:

private var data:videoData = new videoData();
private var xmlData:XML;

private function init():void
{
   addEventListener(Event.ENTER_FRAME , xmlLoaded );
}

private function xmlLoaded(event:Event):void
{
   if( videoData.xmlLoaded )
   {
     xmlData = videoData.getXML();
     removeEventListener(Event.ENTER_FRAME , xmlLoaded );
   }
}

You are already getting your private myXML variable out through the .getXML() method. This is the best way to expose encapsulated data to outside classes.

An alternative would be to make your myXML field public instead of private, but using the get/set accessor methods you are hiding your actual implementation from outside world.

[Edit]

If your getXML() method is returning null, it means that your event handler (the processXML method) has not yet been called.

The problem appears to be in your VideoData constructor:

   public function videoData()
   {
      var myXMLLoader:URLLoader = new URLLoader();
      myXMLLoader.load(new URLRequest("playlist.xml"));
      myXMLLoader.addEventListener(Event.COMPLETE, processXML);
   }

The XML file is probably loaded before you attach the event handler, and that is why the event fires right before you start to listen to it. Try to reverse it and see if it works:

   public function videoData()
   {
      var myXMLLoader:URLLoader = new URLLoader();
      myXMLLoader.addEventListener(Event.COMPLETE, processXML); // moved up
      myXMLLoader.load(new URLRequest("playlist.xml"));
   }