CODEWITHSUNDEEP
flashactionscript-3error-handlingtry-catch
evilpenguin
evilpenguin

Reputation: 5478

try-catch not working?

I'm using a try-catch block in the following Actionscript 3 code:

try {
    this._subtitle = new SubtitleController(subtitlePath, _framerate);
    this._subtitle.addEventListener(Event.COMPLETE, subtitleLoaded);
}
catch (e:Error) {
    trace('subtitle not found');
}

The SubtitleController constructor then tries to load the subtitlePath and throws an Error #2044: Unhandled ioError, but the error is not caught by the try statement. The error is simply thrown like no try statement ever existed.

Sure, I can replace that code with

this._subtitle.addEventListener(IOErrorEvent.IO_ERROR, function (ev:Event) { trace('subtitle not loaded'); });
this._subtitle = new SubtitleController(subtitlePath, _framerate);
this._subtitle.addEventListener(Event.COMPLETE, subtitleLoaded);

and it almost works, it stops trowing that error, but throws another one instead.

But isn't the whole point of try-catch blocks to do that? Why does it not work with the try-catch, but it does work with a regular event listener?

Upvotes: 2

Views: 4375

Answers (3)

Brian Hodge
Brian Hodge

Reputation: 2135

Basically, since the call is async a try..catch..finally block won’t do you a beans bit of good. It takes a while for the loader to determine the url is bad and then it dispatches the IO_ERROR event. -http://www.mattmaher.net/flexible_code/index.php/2008/01/10/urlloader-stream-error-handling/

Theo is correct; I would merely add to use the IOErrorEvent class of the flash.events package to handle this for anyone that did not know the method.

var loader:URLLoader = new URLLoader();
loader.load(new URLRequest("test.mp3"));
loader.addEventListener(IOErrorEvent.IO_ERROR, onIOError);
function onIOError(e:IOErrorEvent):void
{
    trace("An IO Error has occured.\n\n", e);
}

If your working with a Loader object and not the URLLoader, remember that you need to listen to the contentLoaderInfo property of the Loader object as follows.

var loader:Loader = new Loader();
addChild(loader);

loader.contentLoaderInfo.addEventListener(IOErrorEvent.IO_ERROR, onIOError);
loader.load(new URLRequest("path/to/asset"));

function onIOError(e:IOErrorEvent):void
{
    trace("An IO Error has occured.\n\n", e);
}

Upvotes: 6

SketchBookGames
SketchBookGames

Reputation: 516

Today I found having a class named log.as is a bad idea. Errors thrown from this class do not catch in a try-catch.

I think they were fine before. I've been using FlexUnit with unit-tests which expect errors. I have AIR SDK 2.7 installed and recently added AIR SDK 2.01 (for another project) which may have initiated the conflict.

Might be a corner case of the older SDKs or something specific about my build environment.

Renaming the class resolved the problem for me.

Upvotes: 0

Theo.T
Theo.T

Reputation: 9267

IOErrors/NetworkErrors are asynchronous errors. They are not thrown when the method causing them is called as normal runtime errors. Otherwise the execution would have have to stop completely until a (for example) a file is completely loaded ...

Upvotes: 6

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