Challenge

public class CaesarCipher {
    public static void main(String[] args) {
        String[] letters = {"a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", "n", "o", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z"};
        String message1 = "kfzb gly";
        String message2 = "zlab zlab zlab";
        String message3 = "prmbozxifcoxdfifpqfzbumfxifalzflrp";
        String cipher(String msg, int shift) {
            String s = "";
            int len = msg.length();
            for(int x = 0; x < len; x++) {
                letters c = (letters)(msg.charAt(x) + shift);
                if (c > "z")
                    s += (letters)(msg.charAt(x) - (26-shift));
                else
                    s += (letters)(msg.charAt(x) + shift);
            }
            return s;
        }
        System.out.println(cipher(message1, 3));
        System.out.println(cipher(message2, 3));
        System.out.println(cipher(message3, 3));
    }
}
CaesarCipher.main(null);