Cipher.java

public class Cipher {
 public static void main(String[] args) {
 String str = "";
 String enc = encrypt(str);
 System.out.println(str + " " + enc + " " + decrypt(enc));
 }

 public static String encrypt(String text) {
 String result = "";

 for (int i = 0; i < text.length(); i++) {
 char c = text.charAt(i);

 if (c >= 'a' && c <= 'z') {
 if (c == 'z') c = 'a';
 else c = (char) (c + 1);
 }
 else if (c >= 'A' && c <= 'Z') {
 if (c == 'Z') c = 'A';
 else c = (char) (c + 1);
 }
 result += c;
 }
 return result;
 }

 public static String decrypt(String text) {
 String result = "";

 for (int i = 0; i < text.length(); i++) {
 char c = text.charAt(i);

 if (c >= 'a' && c <= 'z') {
 if (c == 'a') c = 'z';
 else c = (char) (c - 1);
 }
 else if (c >= 'A' && c <= 'Z') {
 if (c == 'A') c = 'Z';
 else c = (char) (c - 1);
 }
 result += c;
 }
 return result;
 }
}