Roman.java

package com.example.roman;

/**
 * Created by danielvaughan on 09/10/2014.
 */
public class Roman {
    public String fromArabic(int i) {
        if(i == 0)
            throw new IllegalArgumentException("Zero not allowed");

        StringBuilder romanStr = new StringBuilder();

        RomanSymbol[] symbols = RomanSymbol.values();

        while(i > 0) {
            int enumIndex = 0;
            for (RomanSymbol symbol : symbols) {
                int factor = (int) Math.floor(i / symbol.arabicValue);
                if(factor > 3) {
                    romanStr.append(symbol.romanValue).append(symbols[enumIndex-1].romanValue);
                    i-= (factor * symbol.arabicValue);
                    break;
                } else if (factor > 0 && factor <= 3){
                    romanStr.append(symbol.romanValue);
                    i -= symbol.arabicValue;
                    break;
                }
                enumIndex++;
            }
        }

        return romanStr.toString();
    }

    private enum RomanSymbol {
        THOUSAND(1000, "M"),
        FIVE_HUNDRED(500, "D"),
        HUNDRED(100, "C"),
        FIFTY(50, "L"),
        TEN(10, "X"),
        FIVE(5, "V"),
        ONE(1, "I");

        int arabicValue;
        String romanValue;

        RomanSymbol(int arabicValue, String romanValue) {
            this.arabicValue = arabicValue;
            this.romanValue = romanValue;
        }
    }


}