TypeError: Error #1009: Cannot access a property or method of a null object reference

Hey all. I checked Google and saw tons of results. Read some of the answers and tried to apply the solutions they used. Either it doesn't work or I'm doing something wrong.

I kinda understand the error, but I don't know how to correct it.

This is what I have in one frame. I know, I know...I'll use classes next time. Promise. :crazy:

The error only appeared when I implemented the following bit of code:

Code:

---

if(mcBall.hitTestObject(man))
        {
                gotoAndPlay("gameOver");
        }

---

Code:

---

stop();

// VARIABLES

var ballXSpeed:Number = -8;
var ballYSpeed:Number = -8;

var starXSpeed:Number = 8;
var starYSpeed:Number = 8;

var leftKeyDown:Boolean = false;
var upKeyDown:Boolean = false;
var rightKeyDown:Boolean = false;
var downKeyDown:Boolean = false;

var manSpeed:Number = 7;

// MOVE RED CIRCLE

mcBall.addEventListener(Event.ENTER_FRAME, moveBall);

function moveBall(event:Event):void
{       
        mcBall.x += ballXSpeed;
        mcBall.y += ballYSpeed;
       
        if(mcBall.x >= stage.stageWidth-mcBall.width)
        {
                ballXSpeed *= -1;
        }
       
        if(mcBall.x < 0)
        {
                ballXSpeed *= -1;
        }
       
        if(mcBall.y >= stage.stageHeight-mcBall.height)
        {
                ballYSpeed *= -1;
        }
       
        if(mcBall.y <0)
        {
                ballYSpeed *= -1;
        }       
}


// MOVE STAR

mcStar.addEventListener(Event.ENTER_FRAME, moveStar);

function moveStar(event:Event):void
{       
        mcStar.x += starXSpeed;
        mcStar.y += starYSpeed;
       
        if(mcStar.x >= stage.stageWidth-mcStar.width)
        {
                starXSpeed *= -1;
        }
       
        if(mcStar.x < 0)
        {
                starXSpeed *= -1;
        }
       
        if(mcStar.y >= stage.stageHeight-mcStar.height)
        {
                starYSpeed *= -1;
        }
       
        if(mcStar.y <0)
        {
                starYSpeed *= -1;
        }
       
}

man.addEventListener(Event.ENTER_FRAME, moveMan)

// MOVE PLAYER

function moveMan(event:Event):void
{
        Mouse.hide();
        man.x = mouseX;
        man.y = mouseY;
}


// COLLISION CIRLE AND MAN

// The culprit for messing up

stage.addEventListener(Event.ENTER_FRAME, circleHits);

function circleHits(event:Event):void
{
        if(mcBall.hitTestObject(man))
        {
                gotoAndPlay("gameOver");
        }
}

---

When the collision occurs, it goes to the game over screen but in flash it generates an infinite loop until I close the application.

Here's the bit that loops.

Code:

---

TypeError: Error #1009: Cannot access a property or method of a null object reference.
        at game_fla::MainTimeline/moveBall()
TypeError: Error #1009: Cannot access a property or method of a null object reference.
        at game_fla::MainTimeline/moveStar()
TypeError: Error #1009: Cannot access a property or method of a null object reference.
        at game_fla::MainTimeline/moveMan()
TypeError: Error #1009: Cannot access a property or method of a null object reference.
        at game_fla::MainTimeline/circleHits()

---

Thanks. :cap:

This would be easier looked at with a source file. Could you attach one?

I will say this though, I do not see the mcBall variable declared anywhere.

It looks like mcBall does not exist. Did you forget to name it on your stage? Or is it on the stage at the time this script runs?

Thanks for the help guys.

Also, in the gameOver screen I can't get the mouse to show (it's hidden during the game). I tried Mouse.show(); but it didn't work.

just a hunch, remove eventlisteners before going to a new frame. what could happen is that the functions that are running from the enterframe are still running when you goto game over in which case things IN those functions may not exist anymore such as mcBall or ballXSpeed

so for example:

PHP Code:

---

function circleHits(event:Event):void
{
    if(mcBall.hitTestObject(man))
    {

        man.removeEventListener(Event.ENTER_FRAME, moveMan)
        stage.removeEventListener(Event.ENTER_FRAME, circleHits);
        mcStar.removeEventListener(Event.ENTER_FRAME, moveStar);
        mcBall.removeEventListener(Event.ENTER_FRAME, moveBall);

        gotoAndPlay("gameOver");
    }
} 


---

Yap. that did the trick. No more error messages. Thanks deadlock32. :)