Sum all the elements java arraylist

Question

If I had: ArrayList m = new ArrayList(); with the double values ​​inside, how should I do to add up all the ArrayList elements?

Answer 1

Two ways:

Use indexes:

double sum = 0;
for(int i = 0; i < m.size(); i++)
    sum += m.get(i);
return sum;

Use the "for each" style:

double sum = 0;
for(Double d : m)
    sum += d;
return sum;