NullReferenceException and classes

Question

Okay, I thought I understood all this, but now suddenly I'm at a loss. This NullReferenceException error (Object Reference not set to an instance of an object) gives me little information about what I'm doing wrong.

Basically, I have a class called "trigger", set up as just a bunch of variables like so:

class trigger {
   var name:String = "Idle";
}

Then in another script, I attempt to make an array of these triggers, like so:

public var myCode:trigger[];
public function makeTrigger(howMany:Number){
   myCode = new trigger[howMany];
   Debug.Log("thisTrigger: "+myCode[0].name);
}

It's that Debug.Log line that pops the error. Obviously, anything more I try to do with my trigger class doesn't work. If I debug the length of myCode, I get the right number, but somehow the class is empty. I don't understand.

Any help would be just awesome. Thanks in advance, Jeremy

Answer 1

Best Answer

Answer by yoyo · Feb 11, 2011 at 05:31 PM

You've created an array of trigger references, but you still haven't created the triggers themselves. You need something like ...

public var myCode:trigger[];
public function makeTrigger(howMany:Number){
   myCode = new trigger[howMany];
   for (var i = 0; i < howMany; ++i){
      trigger[i] = new trigger();
   }
   Debug.Log("thisTrigger: "+myCode[0].name);
}

(Apologies if my C# is showing, but you get the idea ...)

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jbalzer · Feb 11, 2011 at 05:35 PM 0

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Ahhhh... thank you. I thought the myCode=new trigger[how$$anonymous$$any] did that automatically. Well, thank you so much. You just saved me hours of frustration.

Jessy · Feb 11, 2011 at 05:38 PM 1

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http://answers.unity3d.com/questions/30470/c-object-array-gives-me-null-objects

NullReferenceException and classes

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