/* 10/16/2019
 Value Methods
 Redo of Lab10 to use methods that return a value
 Use a 2 step solution. First method calculates sum 
 of numbers read in, second method calculates average.
 
 (first we will write a method that adds 2 numbers and 
 returns their sum).
 */
import java.util.Scanner;

public class AverageMethod2 {
  /* main will call and methods and print msgs */
  public static void main(String[] args) {
    // test sum2nums
    // int sum = sum2nums(34, 21); can assign the return value
    System.out.println("in main, sum is: " + sum2nums(34,21));
    // example of composition
    System.out.println("second sum: " +
                       sum2nums(sum2nums(10, 20), 30));
    Scanner sc = new Scanner(System.in);
    System.out.println("How many elements will be processed? ");
    int numElts = sc.nextInt();
    // print average
    // first call the sum method 
    // I am going to save the return value from sum method
    // and use it as the parameter to the call to average
    double sum = sum(numElts, sc); 
    double average = average(numElts, sum);
    System.out.println("average is: " + average);
    // could have done all 3 stmts in one stmt as follows
    System.out.println("average is: " +
                       average(numElts, sum(numElts,sc)));
  }
     
  /** sum reads in a set of numbers and return their sum
    * @param num the number of elements to read in
    * @param keyboard is the Scanner object
    * @return sum of all numbers read in 
    */
  public static double sum(int num, Scanner keyboard) {
    double sum=0.0;
    for (int i=0; i<num; i++) {
      System.out.println("Enter number: ");
      double nextNumber=keyboard.nextDouble();
      sum+=nextNumber;
    }
    return sum;
  }
  /** average accepts number of elements and sum and 
    * simply calculates average and returns it
    * @param num is the number of elements
    * @sum is the sum of all the elements
    * @return sum/num
    */
  public static double average(int num, double sum) {
    //double avg = sum/num;
    //return avg;
    return sum/num;
  }
  /** sum2nums adds 2 integers
    * @param num1 first addend
    * @param num2 second addend
    * @return sum of num1+num2
    * */
  public static int sum2nums(int num1, int num2) {
    int sum = num1 + num2;
    return sum;
  }
}