My Character Won't Move :( Multiple .as files AS3 - actionscript-3

Question

I have a few .as files. They are: MainClass.as, FrontEnd.as, Levels.as, and Hero.as. My problem (as far as I know) is in my Hero.as file. Let me descibe how I have it all set up thusfar because I have been a bit concerned that there are better ways of doing things in AS3.
MainClass.as makes a variable of FrontEnd (menus, namely the main menu) and calls it up (addChild).
FrontEnd.as are my menus. buttons and whatnot...
Levels.as right now just calls up level 1 when the start new game button is pressed on the main menu. Had one hell of a time figuring out how to use functions from a different .as file. Hero.as I will add my code for. I'm posting the whole thing because I don't know where my problem is.
public class Hero extends MovieClip
{
public var roger:player = new player();
private var animationState:String = "down";
public var facing:String = "down";
private var isLeft:Boolean = false;
private var isRight:Boolean = false;
private var isUp:Boolean = false;
private var isDown:Boolean = false;
public var currentPlayer:MovieClip = roger;
public function Hero()
{
addEventListener(Event.ENTER_FRAME, loop);
addEventListener(Event.ADDED_TO_STAGE, onStage);
trace(currentPlayer);
}
public function onStage( event:Event ):void
{
removeEventListener( Event.ADDED_TO_STAGE, onStage );
}
public function addCurrentPlayer():void
{
roger.x = stage.stageWidth * .5;
roger.y = stage.stageHeight * .5;
addChild(roger);
currentPlayer = roger;
setBoundaries();
}
public function keyDownHandler(event:KeyboardEvent)
{
if (event.keyCode == 39)//right press
{
isRight = true;
}
if (event.keyCode == 37)//left pressed
{
isLeft = true;
}
if (event.keyCode == 38)//up pressed
{
isUp = true;
}
if (event.keyCode == 40)//down pressed
{
isDown = true;
}
}
public function keyUpHandler(event:KeyboardEvent)
{
if (event.keyCode == 39)//right released
{
isRight = false;
}
if (event.keyCode == 37)//left released
{
isLeft = false;
}
if (event.keyCode == 38)//up released
{
isUp = false;
}
if (event.keyCode == 40)//down released
{
isDown = false;
}
}
public function loop(Event):void
{
if (currentPlayer == null)
{
addCurrentPlayer();//make sure at least roger is on the screen
}
currentPlayer.addEventListener(KeyboardEvent.KEY_DOWN, keyDownHandler);
currentPlayer.addEventListener(KeyboardEvent.KEY_UP, keyUpHandler);
//----------------------------------0
//Animation States
//----------------------------------0
if (isDown == true)
{
currentPlayer.y += 5;
animationState = "walk_down";
facing = "down";
currentPlayer.gotoAndStop(animationState);
}
else if (isUp == true)
{
currentPlayer.y -= 5;
animationState = "walk_up";
facing = "up";
currentPlayer.gotoAndStop(animationState);
}
else if (isRight == true)
{
currentPlayer.x += 5;
animationState = "walk_right";
facing = "right";
currentPlayer.gotoAndStop(animationState);
}
else if (isLeft == true)
{
currentPlayer.x -= 5;
animationState = "walk_left";
facing = "left";
currentPlayer.gotoAndStop(animationState);
}
//----------------------------------0;
//IDLE STATES
//----------------------------------0
else if (isDown == false)
{
currentPlayer.gotoAndStop(facing);
}
else if (isUp == false)
{
currentPlayer.gotoAndStop(facing);
}
else if (isRight == false)
{
currentPlayer.gotoAndStop(facing);
}
else if (isLeft == false)
{
currentPlayer.gotoAndStop(facing);
}
}
public function setBoundaries():void
{
var halfHeight:int = currentPlayer.height * .5;
var halfWidth:int = currentPlayer.width * .5;
if(currentPlayer.y <= 1)
{
currentPlayer.y += halfHeight;
}
else if(currentPlayer.y > stage.stageHeight)
{
currentPlayer.y -= halfHeight;
}
else if(currentPlayer.x <= 1)
{
currentPlayer.x += halfWidth;
}
else if(currentPlayer.x > stage.stageWidth)
{
currentPlayer.x -= halfWidth;
}
}
}
}
trace(currentPlayer); is giving me [object player] instead of the instance name "roger". (Later on I want more playable characters.) I'm not sure if the problem is there or in my levels file, which I'll post here. (not as long as Hero.as)
public class Levels extends MovieClip
{
var currentLevel:MovieClip;
public function Levels()
{
addEventListener(Event.ADDED_TO_STAGE, onStage);
}
private function onStage(event:Event):void
{
removeEventListener(Event.ADDED_TO_STAGE, gotoLevelOne);
}
public function gotoLevelOne():void
{
var levelOne:LevelOne = new LevelOne();
var hero:Hero = new Hero();
addChild(hero);
levelOne.x = stage.stageWidth * .5;
levelOne.y = stage.stageHeight * .5;
addChild(levelOne);
currentLevel = levelOne;
hero.currentPlayer.x = 100;
hero.currentPlayer.y = 100;
addChild(hero.currentPlayer);
}
}
}
If I remove = roger; from var currentPlayer:MovieClip = roger; it gives me #1009 null object even though I told it in addCurrentPlayer() to change currentPlayer to roger. On level 1, everything shows up but I can't move my character. I know that it worked when I was working on his animations and I would call him to the main menu. Everything worked on him. What's the problem now?

Answer 1

Firstly, there's a lot of things wrong with your code:
In your Hero Class, the 'onStage' Event handler doesn't actually do anything other than remove the event listener that triggers it. While it's good practice to remove the event listener, there should be some other purpose to the Event handler. If there isn't you can remove it and not bother listening for the ADDED_TO_STAGE Event.
Similarly, in your Levels Class 'onStage' Event handler you attempt to remove the event, but name the wrong handler. I assume you want to remove the event handler and then run the 'gotoLevelOne' method. If so, just have the Event.ADDED_TO_STAGE listener call 'gotoLevelOne' and then remove the Event listener there:
public function Levels()
{
addEventListener(Event.ADDED_TO_STAGE, gotoLevelOne);
}
public function gotoLevelOne():void
{
removeEventListener(Event.ADDED_TO_STAGE, gotoLevelOne);
// class continues....
OK, so to your question:
You will be getting the null error because you are referring to currentPlayer from outside the Hero Class, before calling addCurrentPlayer (where it is set).
If you temporarily define currentPlayer as a private variable, the compiler should give you a line number where you first refer to currentPlayer from OUTSIDE the Hero Class (the error will be something like 'Class X is trying to access a private (or non-existent) property of Y Class').
You can then sort out WHY you are accessing currentPlayer before calling addCurrentPlayer. You may also want to think about if currentPlayer NEEDS to be public (if so, then what is 'addCurrentPlayer' for? That function effectively works as a setter for currentPlayer).
EDIT:
At the moment you are adding new KEY_DOWN and KEY_UP event listeners EVERY frame of your game loop. This is unnecessary. Add them both ONCE in the initialisation of your game (perhaps in your Hero's onStage handler), and count on them to trigger the appropriate handlers.
You will want to add the KEY_DOWN and KEY_UP listeners to 'stage', not currentPlayer, so:
stage.addEventListener(KeyboardEvent.KEY_DOWN, keyDownHandler);
stage.addEventListener(KeyboardEvent.KEY_UP, keyUpHandler);
You will need to add the listeners AFTER your Hero instance has been added to the Stage though, so it has access to 'stage'. That's why it makes sense to add the listeners in the Hero's onstage handler.