Better way of making program that calculates sum and average in java

Question

I made a java command line program for calculating sum and average of an arbitary series of numbers, but I am wondering is there any better way for making it shorter and maybe without an array?

public class Main {

    public static void main(String[] args) {
        System.out.println("------------------");
        System.out.println("Program for calculating sum and average of an arbitary series of numbers");
        System.out.println("------------------");

        Scanner input = new Scanner(System.in);

        System.out.print("How many numbers do you want to calculate? ");
        int nums = input.nextInt();
        int array[] = new int[nums];
        int sum = 0;

        for (int i=0; i<nums; i++){
            System.out.print("Enter " + (i+1) + ". number: ");
            array[i] = input.nextInt();
        }

        for (int i=0; i<array.length; i++){
            sum= sum + array[i];
        }
        System.out.println("Sum is: " + sum);
        System.out.print("Average is: " + (sum/nums));
    }
}

@AndyTurner so, what should I use instead of an array, suggest me. And I will surely check out code review. Thanks. — BaDnja, Jun 25 '18 at 13:34
In addition to Andy's suggestion... Also you need a `counter` for the `average` — Yahya, Jun 25 '18 at 13:36
@EmilePels Yes but he ain't need to ask the user two times if he use a `counter` variable — Yahya, Jun 25 '18 at 13:39
@Yahya He isn't asking the user two times, he's asking the user once how many numbers they want to enter. Using a different name for that variable `nums` is not going to change anything. — Erwin Bolwidt, Jun 25 '18 at 13:49
@ErwinBolwidt I did not see that he needed the `nums` in the `for-loop` , that's it. — Yahya, Jun 25 '18 at 13:53

Bill the Lizard · Accepted Answer · 2018-06-25T13:33:26.940

You have two for loops in your code. The first one writes values to an array, and the second one reads them to get their sum. You don't really need both of those loops (or the array). You can sum the values as you read them in, then calculate the average based on the sum.

Note, though, that if you want to extend your code later to calculate other stats on the entered data (e.g., standard deviation) it will be easier to work with the data stored in an array.

score 1 · Answer 2 · answered Jun 26 '18 at 10:13

You don't need to store these numbers to an array.

Usage of BufferedReader is inexpensive over Scanner in this case. Refer reasons to consider using BufferedReader.

public static void main(String[] args) throws IOException {
        System.out.println("------\nProgram for calculating sum and average of integers\n------");
        System.out.print("Enter space separated integer values: ");
        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
        String[] split = reader.readLine().split("\\s");//splits string on whitespaces
        double sum=0, average;
        for (String numberString : split)
            sum += Integer.parseInt(numberString);
        average = sum / split.length;
        System.out.println("Sum: " + sum);
        System.out.println("Average: " + average);
    }

Rene Knop · Answer 3 · 2018-06-26T10:38:33.077

A simple solution, where the user does not have to enter the number of the numbers first.

public static void main(String[] args) {
    System.out.println("------------------");
    System.out.println("Program for calculating sum and average of an arbitary series of numbers");
    System.out.println("------------------");

    Scanner input = new Scanner(System.in);
    ArrayList<Integer> values = new ArrayList<>();

    System.out.print("Input numbers. Input something else (e.g. enter) if you're finisehd:\n");
    while (true) {
        try {
            values.add(Integer.parseInt(input.nextLine()));
        } catch (Exception e) {
            break;
        }
    }
    System.out.println("Sum is : " + values.stream().mapToInt(Integer::intValue).sum());
    System.out.println("Average is: " + values.stream().mapToInt(Integer::intValue).average().getAsDouble());
}

Better way of making program that calculates sum and average in java

3 Answers3