Question

I’ve been debugging the following issue for quite awhile now and have hit a wall.

I’ve set up a project in Flash (CS4, btw) that has a set of keyframes that I move between to represent the various screens of a game. One of them has a MovieClip defined (with children inside it) representing an option menu, that appears on a couple of different keyframes.

The problem I’m having is that this MovieClip reference seems to be accessible when I first enter the keyframe (using “gotoAndStop”), and occassionally when I move to other frames and back. But in at least one case, when I exit the frame and come back, I get a null reference error (TypeError: Error #1009: Cannot access a property or method of a null object reference). when I try and access it (getChildByName(“optionMenuTitle”)). I’ve even tried having the system iterate from 0 to numChildren and print out the name of each object, but it returns NULL at position 7 despite returning numChildren as 9. Does anyone have any idea why this particular MovieClip reference is NULL only in this case??

Here is a basic (abbreviated) rundown of the process occurring:

//set up function to be fired on frame construction
addEventListener(Event.FRAME_CONSTRUCTED, fadeIn, false, 0, true);  

public function fadeIn(event:Event):void {
   _handler.handle(); //this function is called which runs the debug statement below
   trace (mainDoc.numChildren); //displays 9
   for (var i = 0; i < mainDoc.numChildren; i++) { trace(mainDoc.getChildAt(i).name); } //throws null when it gets to 7 
   optionMenuTitle = OptionMenu(mainDoc.getChildByName("optionMenuTitle")); //the original failed call that caused me to debug
}

edit: One other potentially useful bit of information. If I comment out the getChild commands above that error, the frame loads and I can see the MovieClip visually displayed on the stage (although it’s not interactive and is constantly cycling through the frames of its child objects). Still can’t access it programatically though.

another edit: The object in question is a subclass of MovieClip that I named “OptionMenu”. I put a breakpoint in the OptionMenu constructor, and when the frame loads correctly, that breakpoint is hit. When I get the error above, the breakpoint in the constructor is never hit. The debugger doesn’t seem to give me access to see what’s going on inside Flash’s mind when it’s instantiating the frame, however, so I can’t see the logic as to why the constructor is never called.

Answer 1

Well this one has been driving me crazy. I could not workout why it does not reference your optionMenuTitle when you go back to the frame called title a second time.

The only way I could work around it was to take the 3 buttons out of the OptionMenu MovieClip and put them on the stage with the grey background underneath, essentially doing away with OptionsMenu.

So I moved all initialization code from OptionMenu to your TitleHanlder and also added the destroy calls to your destroy method in TitleHandler for each of the 3 buttons.

I also changed the refs from root to mainDoc:

sound.initialize(LogicGameMain(mainDoc).soundOn);
music.initialize(LogicGameMain(mainDoc).musicOn);

This worked for me as you can still interact with the buttons the second time around. It definately seems like there is some bug with these buttons being nested.

I hope this is useful for you.