Roman.java

package org.lodder.subtools.sublibrary.control;


/** Source: http://rosettacode.org/wiki/Roman_numerals/Decode#Java_2 
 * */

public class Roman {
  private static int decodeSingle(char letter) {
    switch (letter) {
      case 'M':
        return 1000;
      case 'D':
        return 500;
      case 'C':
        return 100;
      case 'L':
        return 50;
      case 'X':
        return 10;
      case 'V':
        return 5;
      case 'I':
        return 1;
      default:
        return 0;
    }
  }

  public static int decode(String roman) {
    int result = 0;
    String uRoman = roman.toUpperCase(); // case-insensitive
    for (int i = 0; i < uRoman.length() - 1; i++) {// loop over all but the last character
      // if this character has a lower value than the next character
      if (decodeSingle(uRoman.charAt(i)) < decodeSingle(uRoman.charAt(i + 1))) {
        // subtract it
        result -= decodeSingle(uRoman.charAt(i));
      } else {
        // add it
        result += decodeSingle(uRoman.charAt(i));
      }
    }
    // decode the last character, which is always added
    result += decodeSingle(uRoman.charAt(uRoman.length() - 1));
    return result;
  }
}