AS3 Argument Error #1063 ... expected 1 got 0 - actionscript-3

Question

So I got a very basic class
package {
import flash.display.MovieClip;
public class XmlLang extends MovieClip {
public function XmlLang(num:int) {
trace(num);
}
}
}
and an object at frame one:
var teste:XmlLang = new XmlLang(1);
I'm getting this error:
ArgumentError: Error #1063: Argument count mismatch on XmlLang(). Expected 1, got 0
What am I doing wrong?
Thank you very much for you help.

Answer 1

Something is up with your setup. I took your code and implemented it and it worked.
Here's what I did. I created a new test.fla file in AS3 and put the following code on frame 1 - no object on the stage, just code in frame 1.
import XmlLang;
var teste:XmlLang = new XmlLang(1);
stop();
Created a XmlLang.as file, copying your code exactly and saved it in the same folder as the test.fla. Compiled and got a trace of 1
So I'm not exactly sure what's going on. What version of Flash are you running?

Answer 2

Not sure if this was your case, but for future googlers: you get this error message when you're trying to initialize a vector but then forget the new keyword.
So this:
var something:Vector.<Something> = Vector.<Something>();
Will give you an error saying that Something had an argument count mismatch. The correct line is:
var something:Vector.<Something> = new Vector.<Something>();
Difficult error to get at a glance. Took me a few minutes to find it in my code, especially because it doesn't really give you the error line.

Answer 3

I expect you have an instance of XmlLang located on stage, that will be constructed using a constructor with 0 parameters, like an ordinary MovieClip. To check for this, change the constructor header to this:
public function XmlLang(num:int = 0) {
This way, if something will instantiate an XmlLang without a parameter supplied, the new instance will receive a 0 (the default value) as parameter. And then you check your trace output, I am expecting one or more zeroes appear, followed by an 1.