Calculating average of an array list?

Question

I\'m trying to use the below code to calculate the average of a set of values that a user enters and display it in a jTextArea but it does not work properly. Sa

Answer 1

Correct and fast way compute average for List:

private double calculateAverage(List marks) {
    long sum = 0;
    for (Integer mark : marks) {
        sum += mark;
    }
    return marks.isEmpty()? 0: 1.0*sum/marks.size();
}

This solution take into account:

• Handle overflow
• Do not allocate memory like Java8 stream
• Do not use slow BigDecimal

It works coorectly for List, because any list contains less that 2^31 int, and it is possible to use long as accumulator.

PS

Actually foreach allocate memory - you should use old style for() cycle in mission critical parts