Tracing and storing an array (AS3) - arrays

Question

I have an array in which the response to each question is recorded using a list response. A for loop where once the last question in the array is reached, another button (titled "continue") is made visible. A person clicks this now visible button to continue the task. I have two trace commands in my code, one in the for loop and one in for when the continued button is clicked. The trace function in the for loop works; however, the trace executed in the function when the continue button is clicked returns "undefined" values. (If my description isn't clear, I will make this more concrete using my code below.)
My question is why is it that the exact same value that is being trace would return values in one instance and not the other? My goal is to store the responses to the questions in the array into a String.
var listOfQuestions:Array = new Array;
var listOfAnswers:Array = new Array;
var i:int = 0;
listOfQuestions[0] = "Question 1";
listOfQuestions[1] = "Question 2";
listOfQuestions[2] = "Question 3";
lstResponses.addItem({label: "Response 1", data: "1"});
lstResponses.addItem({label: "Response 2", data: "2"});
lstResponses.addItem({label: "Response 3", data: "3"});
btnNextQuestion.addEventListener(MouseEvent.CLICK, presentNextQuestion);
function presentNextQuestion(evt:MouseEvent){
listOfAnswers[i] = lstResponses.selectedItem.data;
lstResponses.selectedItem = null;
i++;
//Present the element stored in index “i”;
if(i == listOfQuestions.length)
{
txtQuestion.htmlText = "<b>End of list. Click the Continue to Part II for the next part.</b>", btnContinue.visible = true, btnNextQuestion.visible = false;
//Output all the questions and answers;
for (i = 0; i <listOfQuestions.length; i++)
{
trace(i, listOfQuestions[i], listOfAnswers[i]);
}
}
/*If there are more elements left, present the element stored in index “i.”*/
else
{
txtQuestion.htmlText = listOfQuestions[i];
}
}
btnContinue.addEventListener(MouseEvent.CLICK, continueClicked);
function continueClicked(evt:MouseEvent){
trace(listOfAnswers[i]);
}
To reiterate my issue using my code above:
trace(i, listOfQuestions[i], listOfAnswers[i])
yields the anticipated result, i.e., 0 Question 1 [response]. However, the
trace(listOfAnswers[i]);
in the last line of the code yields "undefined".
I've also wondered whether this error was due to the data needing to be converted to a string. In that regard, I added the following code (see below), but the error I received was: Error #1010: A term is undefined and has no properties.
var b:String = new String;
b = listOfAnswers[i].toString()
b = listOfAnswers[i].join("");
Thanks for your time and patience.

Answer 1

The issue appears to be how you're tracing the answer when you click on the continue button. You are tracing the answer at the index of i but your code doesn't prevent i from being incremented past the length of your list.
My guess is you're clicking the next button until it tells you that you have reached the end of the list, then only do you click the continue button. If so, i will be 3, and you're trying to trace listOfAnswers [3] and that is one more than the length of your list, giving you undefined.
Try replacing
trace(listOfAnswers[i]);
with
for (i = 0; i <listOfQuestions.length; i++)
{
trace(listOfAnswers[i]);
}