MyMethod3
ArrayList sum = new ArrayList();
for (i = 0; i < MyArrayList.size(); i++){
    for (j = i + 1; j < MyArrayList.size(); j++){
        for (k = j + 1; k < MyArrayList.size(); k++){
            int total = MyArrayList.get(i) + MyArrayList.get(j) + MyArrayList.get(k);
            sum.add(total);
        }
    }
}
return sum;