Pong classes

//Ball.as
package{
    import flash.display.MovieClip;

    public class Ball extends MovieClip{
        public var xdir = -5;
        public var ydir = 5;
        public function Ball(){
            this.graphics.beginFill(0x000000);
            this.graphics.drawCircle(0,0,10);
        }
        public function update(){
            this.x+=xdir;
            this.y+=ydir;
        }
    }
}

//PlayerBat.as
package{
    import flash.display.MovieClip;
    import flash.events.KeyboardEvent;
    import flash.text.TextField;
    public class PlayerBat extends MovieClip{
        var upkey:Boolean;
        var downkey:Boolean;
        public function PlayerBat(){
            this.graphics.beginFill(0x000000);
            this.graphics.drawRect(0,0,10,50);
        }
        public function init(){
            stage.addEventListener(KeyboardEvent.KEY_DOWN, keyDown);
            stage.addEventListener(KeyboardEvent.KEY_UP, keyUp);
        }

        public function update(){
            //trace(upkey);
            if(upkey){
                this.y-=10;
            }
            if(downkey){
                this.y+=10;
            }
        }

        private function keyDown(keyEvent:KeyboardEvent){
            if(keyEvent.keyCode == 38){
                upkey = true;
            }
            if(keyEvent.keyCode == 40){
                downkey = true;
            }
        }
        private function keyUp(keyEvent:KeyboardEvent){
            if(keyEvent.keyCode == 38){
                upkey = false;
            }
            if(keyEvent.keyCode == 40){
                downkey = false;
            }
        }
    }
}

//EnemyBat.as
package{
    import flash.display.MovieClip;
    public class EnemyBat extends MovieClip{
        public var goal:int = 200;
        public function EnemyBat(){
            this.graphics.beginFill(0x000000);
            this.graphics.drawRect(0,0,10,50);
        }
        public function update(){
            if(goal>this.y){
                this.y+=5;
            }
            if(goal<this.y){
                this.y-=5;
            }
        }
    }
}