CODEWITHSUNDEEP
arraysactionscript-3flashsubstring
user1876246
user1876246

Reputation: 1229

substring from an array as3 **Error #1009: Cannot access a property or method of a null object reference

I am trying to create a matching game where one object in the array hitBoxes is matched to one object in the array hitBoxes2. I have tried to convert the instance name into a string and then used the substring method to match the LAST number in the instance name, if its a match they win. Right now I'm getting the error

TypeError: Error #1009: Cannot access a property or method of a null object reference. at MethodInfo-499()

I'm wondering if anyone can help me. Thanks! 

            var left:String;
            var correct:MovieClip = new Correct;
            var isClicked:Boolean = false;
            var leftClicked:int = 0;

            p3.nextPage.buttonMode = true;
            p3.nextPage.addEventListener(MouseEvent.CLICK, nextPage);

            function nextPage(MouseEvent):void{
                removeChild(p3);
            }

            var hitBoxes:Array = [p3.a1, p3.a2, p3.a3, p3.a4, p3.a5, p3.a6, p3.a7, p3.a8];
            var hitBoxes2:Array = [p3.b1, p3.b2, p3.b3, p3.b4, p3.b5, p3.b6, p3.b7, p3.b8];


            for (var h:int = 0; h < hitBoxes.length; h++){
                hitBoxes[h].buttonMode = true;
                hitBoxes[h].addEventListener(MouseEvent.CLICK, matchingLeft);
            }

            for (var h2:int = 0; h2 < hitBoxes2.length; h2++){
                hitBoxes2[h2].buttonMode = true;
                hitBoxes2[h2].addEventListener(MouseEvent.CLICK, matchingRight);
            }

            function matchingLeft(e:MouseEvent):void{
                var left = String(e.currentTarget.name);
                isClicked = true;
                trace(left);
            }

            function matchingRight(e:MouseEvent):void{
                var right:String = String(e.currentTarget.name);
                trace(right);
                if(isClicked == true && left.substring(3,3) == right.substring(3,3)){
                    trace("matched");
                }

            }

Upvotes: 0

Views: 905

Answers (1)

DigitalD
DigitalD

Reputation: 586

According to your code variable "left" is null at matchingRight method, because matchingLeft uses its local variable with name "left", and top-level "left" still has its default value.

also String.substring method is used incorrectly: 

var name:String="p3.a1";
trace(name.substring(3, 3)); // this will always output empty string ""
trace(name.substring(4, 5)); // this will output "1" string

in conclusion I'd advise to use array indices (integers) instead of strings when calculating "matched" condition, substring operation and string comparison are CPU intensive.

Upvotes: 2

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