Roman Numeral

This is a Java implementation of a Roman numeral class that supports parsing of Roman numeral strings, the conversion between Roman numeral string and Arabic decimal integer representation as well as basic arithmetic and comparison operations.

Here is a quick usage example:

import de.sebastianzander.romannumerals.RomanNumeral;

public class Application
{
    public void main(String[] args)
    {
        // construct from either a Roman numeral string or an Arabic decimal integer
        RomanNumeral a = new RomanNumeral(1987);
        RomanNumeral b = new RomanNumeral("XXXIV");
        RomanNumeral c = RomanNumeral.fromRomanNumeralString("IV");

        // calculate sum of two RomanNumeral objects
        RomanNumeral s = a.add(b);

        // calculate sum of Iterable of RomanNumeral objects
        RomanNumeral t = RomanNumeral.sum(Arrays.asList(a, b, c));

        System.out.printf("%s + %s = %s\n", a, b, s);
        System.out.printf("%d + %d = %d\n", a.arabicDecimal(), b.arabicDecimal(), s.arabicDecimal());
    }
}

The above example should create the following output:

MCMLXXXVII + XXXIV = MMXXI
1987 + 34 = 2021