package weightedavgdataanalyzer;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.util.Scanner;
import java.util.NoSuchElementException;

public class WeightedAvgDataAnalyzer {

   public static void main(String[] args) throws IOException
   {
      Scanner in = new Scanner(System.in);

      boolean done = false;
      while (!done){
         try{
            System.out.print("Please enter the file name: ");
            String filename = in.next();

            double[] data = readFile(filename);



            double sum = 0;
            for (double d : data) { sum = sum + d; }
            System.out.println("The sum is " + sum);

            done = true;
         }
         catch (FileNotFoundException exception){
            System.out.println("File not found.");
         }
         catch (NoSuchElementException exception){
            System.out.println("File contents invalid.");
         }

      }
   }

   public static double[] readFile(String filename) throws IOException
   {
      File inFile = new File(filename);
      try(Scanner in = new Scanner(inFile)) {
         return readData(in);
      }
   }

   public static double[] readData(Scanner in) throws IOException
   {
      int numberOfValues = in.nextInt();
      double[] data = new double[numberOfValues];

      for (int i = 0; i < numberOfValues; i++){
         data[i] = in.nextDouble();
      }

      if (in.hasNext()){
         throw new IOException("End of file expected");
      }
      return data;
   }
}