Hello I was wandering if someone could help, I keep getting this error spat back at me when I try to launch something in as3. Do I need to import something? Apologies, I originally learned AS2 and I'm now slowly learning AS3.
baby steps.
TypeError: Error #1009: Cannot access a property or method of a null object reference.
at draganddropframe1_resetter2_0_fla::MainTimeline/frame3()
at flash.display::Sprite/constructChildren()
at flash.display::Sprite()
at flash.display::MovieClip()
this.window_mc.visible = true;
this.windwo_mc.offwindow.addEventListener(MouseEvent.CLICK, shutwin);
function shutwin(event:MouseEvent):void
{
this.window_mc.visible = false;
}
UPDATES -----------
A method that appears to have worked around it by changing the direct path to 'this'. Clicked inside the movieclip, added a layer called actions and inserted this script that referenced the movieClip I wanted to hide when clicked.
this.addEventListener(MouseEvent.CLICK, fl_ClickToHide);
function fl_ClickToHide(event:MouseEvent):void
{
this.visible = false;
}
The error you are getting means an object, (moveiclip, variable, etc ) doesn't exist.
Go to your publish settings, and check the box that says "permit debugging". Then when you get that error in your output window it will also display the exact line number the error occurred on. That line will probably tell you what object is null.
It looks like you have a typographical error in your second line. This line
this.windwo_mc.offwindow.addEventListener(MouseEvent.CLICK, shutwin);
should be
this.window_mc.offwindow.addEventListener(MouseEvent.CLICK, shutwin);
You've interchanged w and o.
Otherwise, I would suggest doing Ribs's answer.
UPDATES ----------- "from me "
A method that appears to have worked around it by changing the direct path to 'this'. Clicked inside the movieclip, added a layer called actions, and inserted this script that referenced the movieClip I wanted to hide when clicked.
this.addEventListener(MouseEvent.CLICK, fl_ClickToHide);
function fl_ClickToHide(event:MouseEvent):void
{
this.visible = false;
}
Place this script inside the Movie.
Related
I've found lots of questions and answers about this error, but I'm having trouble because my error seems to referencing the function name and not any instance name on my timeline.
Error
TypeError: Error #1009: Cannot access a property or method of a null object reference.
at mpu_fla::MainTimeline/playAnimation()
My Code
myButton.addEventListener(MouseEvent.CLICK, playAnimation);
function playAnimation(e:MouseEvent):void
{
animation_logosout.play();
}
stop();
I'm not quite sure it's telling me it can't find the function name? Any help would be greatly appreciated! I'm new to AS3!
Thanks!
animation_logosout is undefined. Check if the object is present on stage on the same frame, and check if the instance name is set correctly.
I got an error on the output window. I got serval layers, the first layer on frame 2 there is this function wich goes to frame 3 and stops(Located below). But the frame 3 is located on a diffrent layer. The frame 3 dosent has any codes of the frame 2, its simply a empty layer with some graphics. I think it is trying to run the code from frame 2, but it dosen't finds it. I dont know how to solve this problem, but it slows down the application, because the error is looping.
When it goes to a different frame i get the error
(Cannot acces a property of null)
stage.addEventListener(Event.ENTER_FRAME, SquareCircleHit);
function SquareCircleHit(event:Event):void{
if (square.hitTestObject(circle)) {
gotoAndStop(3);
}
}
It might not be the null property, but here's what's up:
Let's say I have this code -
1. someclipthatsinanarray[i].addEventListener(Event.ENTER_FRAME, arrayframe);
2. function arrayframe(e:Event):void
3. {
4. e.currentTarget.removeEventListener(Event.ENTER_FRAME, arrayframe);
5. e.currentTarget.parent.removeChild(e.currentTarget);
6. e.currentTarget = null;
7. }
- and pay attention to line six. I run this in the debugger and get this error:
Error 1119: Line 6, arrayframe: Property is read - only.
What is read only? If null is read - only, then why?
currentTarget is a property of the Event. It is read only and you cannot modify that property.
Here is what I think you desire to do :
someclipthatsinanarray[i].addEventListener(Event.ENTER_FRAME, arrayframe);
// event handler
function arrayframe(e:Event):void
{
var clip:MovieClip = e.currentTarget as MovieClip;
clip.removeEventListener(Event.ENTER_FRAME, arrayframe);
clip.parent.removeChild(clip);
clip = null;
}
As mentioned in the comments this line is not doing what you likely believe it is :
clip = null;
clip was just a local reference to that MovieClip, just the same as the element in the array is just a reference to the MovieClip. So setting clip to null, is not deleting the MovieClip, it's merely just nulling out our reference, which really is not even needed since it's a local variable and it's scope ends upon completion of the handler.
An object is only truly marked for garbage collection once there are no references to the object remaining.
Also important to note that being on the Display List of another object is considered a reference.
e.currentTarget is a property of your event. It is read-only because an event should not be modified after having been dispatched.
Don't worry though, as soon as all the functions listening to this particular event are finished executing their code, the reference to your clip stored in the event will be garbage collected.
public function starttank(event:MouseEvent):void
{
var Tankdrive:TankDrive = new TankDrive();
Tankdrive.tankstart();
}
It's saying that something in that function contains invalid data.
I have no idea what it is, i checked TankDrive and tankstart(); and both are correct, tankstart() is a public function...
I'm stumped...
EDIT: Error:
Error #2136: The SWF file file:///C|/Users/BigRed/Desktop/TankDrive/TankDrive.swf contains invalid data.
at mainmenu/starttank()
That's the error...
And above the starttank() function is still the same...
Ok, I looked over the files.
I'm puzzled by what you are trying to do.
Your Document class is TankDrive, and it creates an instance of mainmenu, which create ANOTHER instance of TankDrive when you click a button. Which is not what I think you want to do, or you think it's allowing you to access your document class. -- it's not. It's attempting to create a whole new instance of your game.
In short, your design is not making sense, and it's also causing a conflict with the document class resulting in that error.
The quick solution is to NOT have your EventListener & handler for the click in the mainmenu class, and then call the tankstart() method of your document class instead of attempting to create a new instance of TankDrive.
First move that listener into the document class and modify like this :
main.enterTank.addEventListener(MouseEvent.CLICK, starttank);
and then move your handler to the TankDrive class and modify as follows :
public function starttank(event:MouseEvent):void
{
tankstart();
}
This is not the only way to do this, and not really the way that I would do it. But I think that discussion is beyond the scope of this question.
If you want you can contact me at prototype.in.training#gmail.com for more details on that.
The problem is that you have an instance name that's also a class name (and the compiler has assumed that you meant to reference the latter). You probably meant to call your TankDrive variable 'tankDrive', so changing your code snippet to the following will probably help:
public function starttank(event:MouseEvent):void
{
var tankdrive:TankDrive = new TankDrive();
tankdrive.tankstart();
}
It's common and recommended to start all public variable names with a lower case letter, private variables with an underscore, and class names with a capital, though this isn't enforced by the language itself, so this kind of thing can happen.
Here are some guides on conventional variable and function naming that can help you keep track of what each of your vars and functions are supposed to do:
http://www.adobe.com/devnet/actionscript/learning/as3-fundamentals/variables.html
http://www.adobe.com/devnet/actionscript/learning/as3-fundamentals/functions.html
Good luck!
I am extremely frustrated. I'm following a tutorial and mimicing it on my own. I have been able to sort out most of the errors so far but this one has me stumped. I have tried replacing all of the class files with the tutorial specimen ones but i still get the error.
TypeError: Error #1009: Cannot access a property or method of a null object reference.
at com.senocular.utils::KeyObject/construct()
at com.senocular.utils::KeyObject()
at com.asgamer.basics1::Ship()
at com.asgamer.basics1::Engine()
Now, not really understanding the error properly I paste dumped the files online for you to look at.
Ship class: textbin.com/78z35
Engine class: textbin.com/32b24
KeyObject class: textbin.com/p2725
As the error still occured when using the specimen class files I really have no idea where to begin. I will gladly try out any suggestions.
Tip: If you allow debugging, the exception will tell you the exact line in the source code where the Error is being thrown. Assuming you're using the Flash IDE, go to publish settings and in the Flash tab check "Permit debugging". This will makes thing much easier for you.
Anyway, you have an error message. If you read it carefully, you can narrow down where the problem is. I don't know if you are a programmer or you have any interest in being one; if you're not, this answer will hopefully solve this particular problem. Anyway, if you don't mind the rambling, let me tell you that if you're interested in becoming a better programmer, paying attention to errors and learning how to debug / troubleshoot problems is one of the most important abilities you need to develop (if not the most important one); so maybe this will give you a few hints you can use to solve other problems as well.
The message says:
Cannot access a property or method of
a null object reference.
This means, at some point, you did something like this:
someobject.someMethod();
or
someobject.someProperty = "foo";
And someobject happened to be null. You can't call methods or access properties of null.
Ok, so now you know, somewhere, a variable had null as its value. Notice that the fact that you define a variable of property doesn't mean it actually holds an object.
This just says that a variable called mySprite can hold an object of the type Sprite:
var mySprite:Sprite;
But until at some point you create a Sprite and assign it to mySprite, the value held by mySprite will be null. If you do:
mySprite.x = 0;
Before initializing mySprite (i.e. before assigning a Sprite to it), you will have this same Null Reference error.
This error message also offers some helpul context, which you can use to your advantage (in them old days... errors in Flash were silent; when things didn't work, you had to manually trace down the problem).
Ok, let's break this error message down:
at com.senocular.utils::KeyObject/construct()
at com.senocular.utils::KeyObject()
at com.asgamer.basics1::Ship()
at com.asgamer.basics1::Engine()
What you have above is called a stack trace. It basically tells you where the code blew up, and also gives you some context: how did you get there.
The first line tells where the error actually occurred. That is, the construct method in the KeyObject object. That method was called from the KeyObject constructor, which was in turn called from the Ship constructor, which was in turn called from the Engine constructor.
Now, let's analyze how you got there, following the stack trace, bottom-up:
Code in Engine constructor:
ourShip = new Ship(stage);
This creates a new Ship object. It passes a reference to the stage to the Ship constructor method.
Code in Ship constructor:
this.stageRef = stageRef;
key = new KeyObject(stageRef);
It grabs the ref passed in the previous step. It stores it and creates a new KeyObject object. The KeyObject constructor is passed a reference to the stage (which is the same ref that was passed from Engine to Ship).
Code in KeyObject constructor:
KeyObject.stage = stage;
keysDown = new Object();
stage.addEventListener(KeyboardEvent.KEY_DOWN, keyPressed);
stage.addEventListener(KeyboardEvent.KEY_UP, keyReleased);
Now we got to the point where the error message told you the problem was. So, somewhere, you are using a variable that holds null and trying to access one of its methods or properties.
This KeyObject stores the reference to stage it was passed in a static variable and creates a new Object object. So far, no problems. KeyObject cannot be null (it's a reference to a Class). The second line itself cannot have this null problem either. So, if this is all the code in that method, the problem has to be either in the third or the fourth line. Both access the stage reference you passed and try to call a method (addEventListener) on it. So if one fails, the other will fail as well. Then, the third line: that's where the problem has to be.
So, at that point stage is null. As said previously, you can't call a method on null, and that's what the error is telling you.
Now, if you get back to the first method call, you can see this is the origin of the problem:
ourShip = new Ship(stage);
You can be pretty sure that, at this point, stage was null. Add that to the fact that Engine extends MovieClip (which is in turn a DisplayObject), and to the fact that any DisplayObject has a reference to the stage object only while it's added to the display list. The conclusion: an instance of Engine was not attached to the display list when its constructor was ran.
A way to fix this (there might be others) could be moving the code in the Engine constructor to a separate function that will be executed only if / when the Engine object has a valid reference to the stage object.
public function Engine() : void {
if(stage) {
initialize();
} else {
addEventListener(Event.ADDED_TO_STAGE,initialize);
}
}
private function initialize(e:Event = null):void {
removeEventListener(Event.ADDED_TO_STAGE,initialize);
// here goes the code that's currently in Engine constructor
}
Hope this helps.
I have a feeling your stage property is null.
You have have to test this yourself with a trace of the stage object.
In the first line in the constructor of you Engine class, add:
trace(stage);
Add that just above this line:
ourShip = new Ship(stage);
If it traces "null" then that is your problem.