public class Roman {

   private String[] r = {"M", "CM", "D", "CD",
                         "C", "XC", "L", "XL",
                         "X", "IX", "V", "IV",
                         "I" };
   private int[]   rv = {1000, 900, 500, 400,
                         100,  90,  50,  40,
                         10,   9,   5,   4,
                         1 };

   public String roman(int rom) {
      String s = new String();
      for (int i = 0; i < 13; i++) {
         while (rom >= rv[i]) {
            rom -= rv[i];
            s += r[i];
         }
      }
      return s;
   }

   public static void main(String[] args) {
      Roman r = new Roman();
      int n = Integer.parseInt(args[0]);
      String romN = r.roman(n);
      System.out.println(n + " in Roman Numerals is " + romN);
   }
}

% javac Roman.java
% java Roman 3947
3947 in Roman Numerals is MMMCMXLVII
% java Roman 3999
3999 in Roman Numerals is MMMCMXCIX
% java Roman 2888
2888 in Roman Numerals is MMDCCCLXXXVIII
% java Roman 1444
1444 in Roman Numerals is MCDXLIV