RomanNumbers.java

import java.util.Scanner;

/**
 * Created by Connor on 10/5/15.
 */
public class RomanNumbers {

    public int input;

    //parametrized constructor
    public RomanNumbers(int number) {
        input = number;
    }

    public String getRoman() {

        //formatting the input to always have four numbers ex. 0013
        String formattedInput = "";
        String numSTR = Integer.toString(input);
        int length = numSTR.length();
        if (length < 4) {
            if (length == 1) {
                formattedInput = "000" + numSTR;
            }
            if (length == 2) {
                formattedInput = "00" + numSTR;
            }
            if (length == 3) {
                formattedInput = "0" + numSTR;
            }

        } else {
            formattedInput = numSTR;
        }

        //getting digits off the number
        int ones = Integer.parseInt(formattedInput.substring(3));
        int tens = Integer.parseInt(formattedInput.substring(2, 3));
        int hundreds = Integer.parseInt(formattedInput.substring(1, 2));
        int thousands = Integer.parseInt(formattedInput.substring(0, 1));

        //finding romanThousands
        String romanThousands;
        if (thousands > 0 ) {
            romanThousands = "MMMMM".substring(0, thousands);
        }
        else {
            romanThousands = "";
        }

        //finding romanHundreds
        String romanHundreds;
        if (hundreds <= 3 && hundreds != 0)
            romanHundreds = "CCCCC".substring(0, hundreds);
        else if (hundreds == 4)
            romanHundreds = "CD";
        else if (hundreds <= 8 && hundreds != 0)
            romanHundreds = "DCCCC".substring(0, hundreds -4);
        else if (hundreds == 9)
            romanHundreds = "CM";
        else
            romanHundreds = "";

        //finding romanTens
        String romanTens;
        if (tens <= 3 && tens != 0)
            romanTens = "XXXXX".substring(0, tens);
        else if (tens == 4)
            romanTens = "XL";
        else if (tens <= 8 && tens != 0)
            romanTens = "LXXXX".substring(0, tens -4);
        else if (tens == 9)
            romanTens = "XC";
        else
            romanTens = "";

        ////finding romanOnes
        String romanOnes;
        if (ones <= 3)
            romanOnes = "IIIII".substring(0, ones);
        else if (ones == 4)
            romanOnes = "IV";
        else if (ones <= 8)
            romanOnes = "VIIII".substring(0, ones -4);
        else if (ones == 9)
            romanOnes = "IX";
        else
            romanOnes = "0";

        //printing all of the roman numbers in order
        return romanThousands + romanHundreds + romanTens + romanOnes;
    }
}


import java.util.Scanner;

/**
 * Created by Connor on 10/5/15.
 */
public class RomanTester
{
    public static void main(String [] args) {
        Scanner key = new Scanner(System.in);
        System.out.println("Enter an integer: ");
        int input = key.nextInt();


        RomanNumbers num1 = new RomanNumbers(input);


        System.out.println(input + " in Roman Numerals is: " + num1.getRoman());
    }


}