Conversion.java

/*
 * Copyright (C) 2012 Sebastian Straub <sebastian-straub@gmx.net>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
package de.nx42.wotcrawler.util;

/**
 * static number conversions that are not provided by java
 * 
 * @author Sebastian Straub <sebastian-straub@gmx.net>
 */
public class Conversion {
    
    /**
     * Licensed under CC BY-SA 3.0 by Ravindra Gullapalli:
     * http://stackoverflow.com/questions/9073150/converting-roman-numerals-to-decimal
     * 
     * Converts roman numbers to java integers
     * @param romanNumber the roman number string to convert
     * @return java integer representation
     */
    public static int romanToDecimal(String romanNumber) {
        
        int decimal = 0;
        int lastNumber = 0;
        String romanNumeral = romanNumber.toUpperCase();
        
        for (int x = romanNumeral.length() - 1; x >= 0; x--) {
            char convertToDecimal = romanNumber.charAt(x);

            switch (convertToDecimal) {
                case 'M':
                    decimal = processDecimal(1000, lastNumber, decimal);
                    lastNumber = 1000;
                    break;

                case 'D':
                    decimal = processDecimal(500, lastNumber, decimal);
                    lastNumber = 500;
                    break;

                case 'C':
                    decimal = processDecimal(100, lastNumber, decimal);
                    lastNumber = 100;
                    break;

                case 'L':
                    decimal = processDecimal(50, lastNumber, decimal);
                    lastNumber = 50;
                    break;

                case 'X':
                    decimal = processDecimal(10, lastNumber, decimal);
                    lastNumber = 10;
                    break;

                case 'V':
                    decimal = processDecimal(5, lastNumber, decimal);
                    lastNumber = 5;
                    break;

                case 'I':
                    decimal = processDecimal(1, lastNumber, decimal);
                    lastNumber = 1;
                    break;
            }
        }
        return decimal;
        
    }
    
    /**
     * Subroutine for the romanToDecimal method
     */
    private static int processDecimal(int decimal, int lastNumber, int lastDecimal) {
        if (lastNumber > decimal) {
            return lastDecimal - decimal;
        } else {
            return lastDecimal + decimal;
        }
    }

}