AS3 Run gotoAndStop from a class - actionscript-3

Question

I have the problem with Actionscript 3.0 in Adobe Flash. I can't run "gotoAndStop" from a class (not document class).
With the help of the Internet I tried several things, but none of them worked:
1)
MovieClip(root).gotoAndStop(3);
2)
package
{
import flash.display.MovieClip;
public class CustomClassName extends MovieClip
{
public static var mainTimeline:MovieClip;
public function CustomClassName()
{
// constructor code
}
}
}
3)
public class np extends SimpleButton {
var _root:MovieClip;
public function np() {
this.addEventListener(Event.ADDED_TO_STAGE,init);
this.addEventListener(MouseEvent.CLICK,nextF);
}
private function init(e:Event):void{
_root = MovieClip(this.root);
}
private function nextF(e:MouseEvent):void{
_root.addEventListener(Event.RENDER,renderF);
stage.invalidate();
_root.nextScene();
}
private function renderF(e:Event):void {
_root.gotoAndStop(5);
}
}
I have these imports:
import flash.display.MovieClip;
import flash.display.Graphics;
import flash.display.Stage;
import flash.events.Event;
And if I run these lines of code:
trace('frame:',currentFrame);
super(this).gotoAndPlay(2);
trace('frame:',currentFrame);
... I get 0 as currentFrame as a result.
I have a class where I want to run gotoAndStop(2).
And in my .fla file I have these in the first frame:
stop();
import Buzzer.*;
var buzzerClip:Buzzer = new Buzzer();
stage.addChild(buzzerClip);
But the code doesn't run the gotoAndStop function. And actually no error will be returned. Does someone has another idea?

Answer 1

The property root is null until the display object has been added to the display list.
So to adjust your first attempt:
public function MyDisplayObject()
{
init();
}
private function init():void
{
addEventListener(Event.ADDED_TO_STAGE, addedToStageHandler);
}
private function addedToStageHandler()
{
MovieClip(root).gotoAndStop(3);
}