Averages after the loop

An average needs both a sum and a count: it's the sum divided by the count. The loop collects the two, and the average is calculated after the loop, once all the numbers are in:

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int count = 0;
        int sum = 0;
        while (true) {
            int number = Integer.valueOf(scanner.nextLine());
            if (number == 0) {
                break;
            }
            count++;
            sum += number;
        }
        if (count == 0) {
            System.out.println("No numbers");
        } else {
            double average = (double) sum / count;
            System.out.println("Average: " + average);
        }
    }
}

4
5
8
0

Average: 5.666666666666667

Two details matter:

• (double) sum / count turns the sum into a double before dividing, so the decimals are kept (module 4 showed why).
• With no numbers at all, count is 0, and there's no average to show. The if checks for that before dividing.