What causes stack overflows to occur? Why do these lines cause stack overflowing and how do I fix it? - actionscript-3

Question

I'm getting stack overflow errors and i'm not sure what a stack overflow error is or how to fi it. I've looked online to try to understand stack overflows but i'm pretty lost. If anyone could explain to me what in my code is causing the overflow that'd be great
Here is my Hero class:
package {
import flash.events.Event;
import flash.events.KeyboardEvent;
import flash.display.MovieClip;
public class Hero extends DocumentMainNew
{
public var health:Number;
public var mana:Number
public var vx:Number;
public var vy:Number;
public var allowJump:Boolean;
public var collision:Boolean;
public function Hero():void
{
this.addEventListener(Event.ENTER_FRAME, enterFrameHandler);
stage.addEventListener(KeyboardEvent.KEY_DOWN, keyDownHandler);
stage.addEventListener(KeyboardEvent.KEY_UP, keyUpHandler);
}
public function enterFrameHandler(e:Event):void
{
//Gravitates the player
vy += 2;
//Moves the player
angela.x += vx;
angela.y += vy;
//processes collisions
processCollisions();
//scrolls the stage
scrollStage();
}
public function keyDownHandler(e:KeyboardEvent):void
{
switch (e.keyCode)
{
case 37: //left arrow
vx = -7;
break;
case 39: //right arrow
vx = 7;
break;
case 38: //up arrow
if(allowJump)
{
vy = -20;
}
break;
default:
}
}
public function keyUpHandler(e:KeyboardEvent):void
{
switch (e.keyCode)
{
case 37:
vx = 0;
break;
case 39:
vx = 0;
break;
case 38:
break;
default:
}
}
public function processCollisions():void
{
//detects when player is falling
if(vy > 0)
{
//respawns the player if they fell of the stage
if(angela.y > stage.stageHeight)
{
angela.x = _startMarker.x;
angela.y = _startMarker.y;
_boundaries.x = 0;
_boundaries.y = 0;
vy = 0;
}
//otherwise, processes collisions with boundaries
while(_boundaries.hitTestPoint(angela.x, angela.y, true))
{
allowJump = true;
angela.y -= 0.1
vy = 0;
}
}
}
}
}
And here is my main document:
package {
import flash.display.MovieClip
import flash.events.Event
import flash.events.KeyboardEvent
import Hero
public class DocumentMainNew extends MovieClip
{
public var angela:Hero = new Hero;
public var enemy1:Enemy = new Enemy;
public var _boundaries:Boundaries;
var _startMarker:StartMarker;
public function DocumentMainNew():void
{
_startMarker.visible = false;
addChild(angela);
addChild(enemy1);
angela.health = 100;
angela.mana = 100;
stage.focus = stage;
}
public function scrollStage():void
{
_boundaries.x += (stage.stageWidth * 0.5) - angela.x;
angela.x = stage.stageWidth * 0.5;
enemy1.x = _boundaries.x + 30;
_powerup.x = _boundaries.x - 200;
}
}
}
Heres the error:
Error: Error #1023: Stack overflow occurred.
at DocumentMainNew()[/Users/s2111908/Desktop/Game/DocumentMainNew.as:9] at Hero()[/Users/s2111908/Desktop/Game/Hero.as:16]
Line 9 of DocumentMainNew is: public var angela:Hero = new Hero;
Line 16 of Hero is: public function Hero():void
It says at DocumentMainNew() and at Hero() many many times but i didn't want to paste all of it. If the number of times is important let me know and i'll ad a picture. I'm fairly new to AS3 so if anyone has any tips on how to improve my code in anyway please let me know.

Answer 1

First. Please learn how to format your code while posting. The whole code block must be indented. There's a {} button just for that.
Second. Your mistake is Hero extending DocumentMainNew class. The problem is not extending itself but the fact you call new Hero in the DocumentMainNew variable declaration area. Lets see, how it goes.
Root instance of DocumentMainNew is created.
Declaring angela variable and assigning a new Hero to it.
An instance of Hero is created.
Hero is extending DocumentMainNew so the superclass initializes first.
Declaring angela variable and assigning a new Hero to it.
An instance of Hero is created.
...and so on.
I don't know why did you inherited the Hero class from the DocumentMainNew class, but that was a totally wrong move. You should explain what you did try to solve doing so. It should probably be solved in a very different way.