How do I multiply the values in two array list, in order to find the total?

Issue

I am trying to calculate the total cost of items in the users cart. My approach to this is to store the item cost as well as the quantity in an ArrayList and then multiply the value then add it. For example this is my ArrayList. I would like to do

2.00 * 5.00 + 3.00 * 6.00 + 4.00 * 7.00 + 5.00 * 8.00

What I have done so far multiplies the first number in the ArrayList by every item in the ArrayList. This is not what I am trying to do. Can someone help with this?

quaninityArrayList [2.0, 3.0, 4.0, 5.0]
priceArraListy[5.0, 6.0, 7.0, 8.0]

---

ArrayList<Double>  priceArrayList = new ArrayList<>();
ArrayList<Double>  quantitiyArrayList = new ArrayList<>();

quantitiyArrayList.add(2.00);
quantitiyArrayList.add(3.00);
quantitiyArrayList.add(4.00);
quantitiyArrayList.add(5.00);

priceArrayList.add(5.00 );
priceArrayList.add(6.00 );
priceArrayList.add(7.00 );
priceArrayList.add(8.00 );

for(int i = 0; i<quantitiyArrayList.size(); i++){
    for(int j = 0; j< priceArrayList.size(); j++){
              System.out.println(quantitiyArrayList.get(i)*priceArrayList.get(j));
    }
}

Solution

I did it like this:

 //do calculations.
        double sum = 0.0;
        for (int i = 0; i < quantityArrayDouble.length; i++) {
            sum += quantityArrayDouble[i] * priceArrayDouble[i];
        }
        Log.i("sum", sum + "");

Answered By - Teerexmixdoodlejump