package org.jb; public class XD { private int shift; public XD(int shift) { this.shift = shift; } public static void main(String[] args) { // TODO Auto-generated method stub XD app = new XD(-3); String name = "XD"; String cipher = app.encode(name); System.out.println(name + "--->" + cipher); System.out.println(cipher + "--->" + name); } public String transform(String text, int shift) { char [] a = new char[text.length()]; for (int i = 0; i < a.length; i++) { int diff = text.charAt(i) - 'A' + shift; if (diff < 0) diff+=26; if (diff >= 26) diff%= 26; a[i] = (char) ('A' + diff); } return String.valueOf(a); } public String encode(String text) { return transform(text, shift); } public String decode(String cipher) { return transform(cipher, -shift); } }