// This program reads a message and a secret key from the user and
// encrypts the message using a Caesar cipher, shifting each letter.
import java.util.*;

public class SecretMessage {
   public static void main(String[] args) {
      Scanner console = new Scanner(System.in);

      System.out.print("Your secret message: ");
      String message = console.nextLine();
      
      System.out.print("Your secret key: ");
      int key = console.nextInt();
      
      System.out.println("The encoded message: " + encode(message, key));
   }
   
   // This method encodes the given text string using a Caesar
   // cipher, shifting each letter by the given number of places.
   public static String encode(String text, int shift) {
      text = text.toLowerCase();
      String result = "";
      for (int i = 0; i < text.length(); i++) {
         char letter = text.charAt(i);
         result += encodeLetter(letter, shift);
      }
      return result;
   }
   
   // Encodes a single letter using a Caesar cipher.  Shifts only
   // letters (leaves other characters alone).  Assumes letter is
   // lowercase.
   public static char encodeLetter(char letter, int shift) {
      if (letter >= 'a' && letter <= 'z') {
         letter = (char)(letter + shift);
         // may need to wrap around
         if (letter > 'z') {
            letter = (char)(letter - 26);
         } else if (letter < 'a') {
            letter = (char)(letter + 26);
         }
      }
      
      return letter;
   }
}