AS3: Error 1009: Null reference - actionscript-3

Question

I am making a game in ActionScript 3. I have a Menu Class with a method that renders a Menu.
I make an instance of Menu in my Main class, and then call the method. When I debug the application I get a null reference error. This is the code of the menu class:
package
{
import flash.display.MovieClip;
import menucomponents.*;
public class Menu extends MovieClip
{
public function Menu()
{
super();
}
public function initMenuComponents():void{
var arrMenuButtons:Array = new Array();
var btnPlay:MovieClip = new Play();
var btnOptions:MovieClip = new Options();
var btnLikeOnFacebbook:MovieClip = new LikeOnFacebook();
var btnShareOnFacebook:MovieClip = new ShareOnFacebook()
arrMenuButtons.push(btnPlay);
arrMenuButtons.push(btnOptions);
arrMenuButtons.push(btnLikeOnFacebbook);
arrMenuButtons.push(btnShareOnFacebook);
var i:int = 0;
for each(var item in arrMenuButtons){
item.x = (stage.stageWidth / 2) - (item.width / 2);
item.y = 100 + i*50;
item.buttonMode = true;
i++;
}
}
}
}
Thanks in advance.

Answer 1

Your issue is likely that stage is not populated yet when your for loop runs. Try the following:
public class Main extends MovieClip {
public function Main() {
super();
var menu:Menu = new Menu();
//it's good practice - as sometimes stage actually isn't populated yet when your main constructor runs - to check, though in FlashPro i've never actually encountered this (flex/flashBuilder I have)
if(stage){
addedToStage(null);
}else{
//stage isn't ready, lets wait until it is
this.addEventListener(Event.ADDED_TO_STAGE,addedToStage);
}
}
private function addedToStage(e:Event):void {
menu.addEventListener(Event.ADDED_TO_STAGE,menuAdded); //this will ensure that stage is available in the menu instance when menuAdded is called.
stage.addChild(menu);
}
private function menuAdded(e:Event):void {
menu.initMenuComponents();
}
}