New to Java

Hi Guys , I am rather new to Java and I am trying to extend the ArrayList object to that when an ArrayList of Integers exists it has a function to return the Average value of the Integers within the ArrayList. Below is the code I have so far:

import java.util.*;*
*import java.lang.*;
public class MathArrayList<Integer> extends ArrayList<Integer> {

double average;

public double Average() {
CalculateAverage();

return average;
}

private void CalculateAverage() {
double total = 0;

for(int i = 0; i < size(); i++) { 

total += get(i).intValue();
}

average = total / size();
}
}

When I attempt to compile this code I get: Cannot find symbol - Line 18 - ".intValue()" and I cannot work out why! I have created a smaller java project to test that I am using the method '.intValue()' correctly and it is converting and Integer to an int fine! Why cannot it not find a symbol?

Any help/comments if much appricated!

Thanks, Stewart