Rot13Codec Implementation for Java. Can decode offensive linux fortunes with this badboy.

Rot13Codec.java

package com.zombietank.util;

public class Rot13Codec {

    /***
     * encode(encode(input)) = input
     */
    public static String decode(final String input) {
        return encode(input);
    }
   
    public static String encode(final String input) {
        StringBuilder encoded = new StringBuilder(input.length());
        for (char character : input.toCharArray()) {
            encoded.append(Character.isLetter(character) ? rot13(character) : character);
        }
        return encoded.toString();
    }
   
    private static char rot13(char letter) {
        int shift = Character.toUpperCase(letter) <= 'M' ? 13 : -13;
        return (char)(letter + shift);
    }
   
    private Rot13Codec() {
    }
}