Encryption.java

package encryption;

import java.io.*;
class Main {
    public static char normalChar[]
            = {'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'};

    public static char codedChar[]
            = {'Q', 'W', 'E', 'R', 'T', 'Y', 'U', 'I', 'O',
            'P', 'A', 'S', 'D', 'F', 'G', 'H', 'J', 'K',
            'L', 'Z', 'X', 'C', 'V', 'B', 'N', 'M'};

    public static String stringEncryption(String s) {
        // initializing an empty String
        String encryptedString = "";

        // comparing each character of the string and
        // encoding each character using the indices
        for (int i = 0; i < s.length(); i++) {
            for (int j = 0; j < 26; j++) {

                // comparing the character and
                // adding the corresponding char
                // to the encryptedString
                if (s.charAt(i) == normalChar[j]) {
                    encryptedString += codedChar[j];
                    break;
                }

                // if there are any special characters
                // add them directly to the string
                if (s.charAt(i) < 'a' || s.charAt(i) > 'z') {
                    encryptedString += s.charAt(i);
                    break;
                }
            }
        }

        // return encryptedString
        return encryptedString;
    }

    static void rotate()
    {
        int i = 0, j = codedChar.length - 1;
        while(i != j)
        {
            char temp =codedChar[i];
            codedChar[i] = codedChar[j];
            codedChar[j] = temp;
            i++;
        }
    }

    // Function which returns decryptedString
    public static String stringDecryption(String s) {

        // Initializing the string
        String decryptedString = "";

        // Run the for loop for total string
        for (int i = 0; i < s.length(); i++) {
            for (int j = 0; j < 26; j++) {
                if (s.charAt(i) == codedChar[j]) {
                    decryptedString += normalChar[j];
                    break;
                }

                // Add the special characters directly to
                // the String
                if (s.charAt(i) < 'A' || s.charAt(i) > 'Z') {
                    decryptedString += s.charAt(i);
                    break;
                }
            }
        }

        // return the decryptedString
        return decryptedString;
    }

    public static void main(String args[]) {
        String str = "JAVA Encryption";

        // print plain text
        System.out.println("Plain text: " + str);

        // Changing whole string to lower case
        // function call to stringEncryption and storing in
        // encryptedString
        String encryptedString = stringEncryption(str.toLowerCase());

        // printing encryptedString
        System.out.println("Encrypted message: "
                + encryptedString);
        System.out.println("Decrypted message: "
                + stringDecryption(encryptedString));
        rotate();

    }
}