import java.util.Scanner;

public class RomanNumeralCalculator
{
public static void main(String[] args)
{
   Scanner input = new Scanner(System.in);
   int num;

   do
   {
         System.out.println("Please enter an integer from 1 to 5999. Enter a negative number to exit.");
         System.out.print("-> ");
         num = input.nextInt();

         if (num <= 0) System.exit(0);

         if (num < 6000)
         {
            String roman = "";

            while (num >= 1000)
            {
               roman += "M";
               num -= 1000;
            }

            switch (num / 100)
            {
               case 0:
               case 1:
               case 2:
               case 3:
                     break;
               case 4:
                     roman += "CD";
                     num -= 400;
                     break;
               case 5:
               case 6:
               case 7:
               case 8:
                     roman += "D";
                     num -= 500;
                     break;
               case 9:
                     roman += "CM";
                     num -= 900;
                     break;
               default:
                     System.err.println("There is a problem with the hundreds place.");

            }


            while (num >= 100)
            {
               roman += "C";
               num -= 100;
            }

            switch (num / 10)
            {
               case 0:
               case 1:
               case 2:
               case 3:
                     break;
               case 4:
                     roman += "XL";
                     num -= 40;
                     break;
               case 5:
               case 6:
               case 7:
               case 8:
                     roman += "L";
                     num -= 50;
                     break;
               case 9:
                     roman += "XC";
                     num -= 90;
                     break;
               default:
                     System.err.println("There is a problem with the tens place.");
            }

            while (num >= 10)
            {
               roman += "X";
               num -= 10;
            }

            switch (num)
            {
               case 0:
               case 1:
               case 2:
               case 3:
                     break;
               case 4:
                     roman += "IV";
                     num -= 4;
                     break;
               case 5:
               case 6:
               case 7:
               case 8:
                     roman += "V";
                     num -= 5;
                     break;
               case 9:
                     roman += "IX";
                     num -= 9;
                     break;

               default:
                     System.err.println("There is a problem with the units place.");
            }

            while (num > 0)
            {
               roman += "I";
               num

Learning​ ​Objective:​ ​​ ​​Learning​ ​how​ ​to​ ​write​ ​methods...

Learning Objective: Learning how to write methods...