Question

Revise the MeanMedian class so that the user can enter any number of values up to 20. If the list has an even number of values, the median is the numeric average of the values in the two middle positions. Allow the user to enter 9999 to quit entering numbers.   

Answer 1

`Hey,

Note: Brother if you have any queries related the answer please do comment. I would be very happy to resolve all your queries.

import java.util.Scanner;
import java.util.Arrays;
import java.util.ArrayList;

public class Median2
{
   public static double getMedian(double[] nums)
   {
       double median = 0.0;
       int[] middle = new int[2];
      
       if (nums.length % 2 == 0)
       {
           middle[0] = (nums.length / 2) - 1;   // nums.length counts from "1" instead of "0"
           middle[1] = middle[0] + 1;            // get the other middle value in an even length array
           median = nums[middle[0]] + nums[middle[1]];
           median = median / 2.0;
       }
       else
       {
           middle[0] = nums.length / 2;
           median = nums[middle[0]];
       }
      
       return median;
   }
  
   public static void main(String[] args)
   {
       Scanner input = new Scanner(System.in);
      
       final byte LIMIT = 20;        // Maximum number of values to accept.
                                   // Is a byte because why not save a few bytes of memory
      
       int i = 0;                    // iterator for the input loop
      
       String userInput = "";
       ArrayList<String> numberList = new ArrayList<String>();
      
       double[] numbers;
      
       System.out.println("Please enter up to " + LIMIT + " numbers.\nTo stop just enter 9999");
       do
       {
           System.out.print("Number " + (i + 1) + "/" + LIMIT + ": ");
           userInput = input.nextLine().toLowerCase();
           if (!userInput.equals("9999"))
           {
               try
               {
                   Double.parseDouble(userInput);
                   numberList.add(userInput);
                   i++;
               }
               catch (Exception e)
               {
                   System.out.println("Error: " + userInput + " is not a valid number");
                   if (userInput.indexOf(' ') > -1)
                       System.out.println("Please use a single line for each number.");
               }
           }
       } while (!userInput.equals("9999") && i < LIMIT);
      
       if (numberList.size() == 0)
       {
           System.out.println("\nNothing was entered exiting...");
           return; // Kills program if not even one value was entered
       }
       else
       {
           numbers = new double[numberList.size()]; // Create an array the same size as the List
       }
      
       for(int c = 0; c < numberList.size(); c++)
           numbers[c] = Double.parseDouble(numberList.get(c).toString());           // Transfer list values to the array
      
       Arrays.sort(numbers);
      
       System.out.print("\n\nYou entered: ");
       for(Double num : numbers)
           System.out.print(num + " ");
      
       System.out.println("\nThe median value is " + getMedian(numbers));
      
       input.close();
   }
}

Kindly revert for any queries

Thanks.