Homework # 8

/*Kyle Blanchard
  CSCI-111
  Homework 8
  Due 11/27/13
  Kwblanchard@student.stcc.edu*/

import java.io.*;
import java.util.Scanner;

public class Homework8 {

    public static void main(String[] args) {

        Scanner in = promptUser();
        double array[] = arrayFromFile(in);
        System.out.println("Mean: " + meanFromFile(array));
        System.out.println("standardDeviation: " + sdFromFile(array));

    }



// *************************************************************

    private static Scanner promptUser() {

        Scanner in = new Scanner(System.in);
            System.out.println("Please enter the file name: ");
            String fName = in.nextLine();
            in.close();
            File readFile = new File(fName);
            Scanner input = null;
            try {
                    input = new Scanner(readFile);
            } catch (FileNotFoundException e) {
                    System.out.println("Please enter a valid file name.");
            }
            return input;
    }

// *************************************************************

    private static double[] arrayFromFile(Scanner in) {

        int totalNumberOfValues = in.nextInt();
            double arrayFromFile[] = new double[totalNumberOfValues];
            for (int i = 0; i < totalNumberOfValues; i++)
                   arrayFromFile[i] = in.nextDouble();
            return arrayFromFile;
    }

// *************************************************************

    public static double meanFromFile(double[] array) {

        double sum = 0;
        for (int i = 0; i < array.length; i++) {
            sum += array[i];
        }
        return sum / array.length;
    }

// *************************************************************

    public static double sdFromFile(double[] array) {

        double sum = 0;
        for (int i = 0; i < array.length; i++) {
            sum += (Math.pow((array[i] - meanFromFile(array)), 2));
        }
        return Math.sqrt(sum / (array.length - 1));
    }


}