Encryption

Encryption is the technique of coding message to maintain their secrecy. A string of size ‘n’ where n is greator than 1 and less than 10, stores single sentences (each sentence ends with a full Stop ) in each row of the array.

Write a program to accept the size of the array. Display an appropriate message if the size is not satisfying the given condition. Define a string array of the input size and fill it with sentence row-wise.

Change the sentence of the odd rows with an encryption of tho characters ahead of  the original characters. Also change the sentence of the even rows by sorting the sentence in reverse order/

Display the encrypt sentences as per the sample data given below:

Test your program with some sample data and some random data.

Input:          N=4

                             IT IS CLOUDY.

                             IT MAY RAIN.

                             THE WEATHER IS FINE.

                             IT IS COOL.

OUTPUT:

                             KV KU ENQWFA.

                             RAIN MAY IT.

                             VJG YGCV JGT KU HKPG.

                             COOL IS IT.

Solution:-

import java.util.*;

class sentence

{

     String str[],s;

     int i,n;

     String input()

     {

           Scanner sc=new Scanner (System.in);

           return sc.nextLine();

     }

     void takeString()

     {

           Scanner sc=new Scanner (System.in);

           System.out.println("How many sentences:");

           n=sc.nextInt();

           if(n<1||n>9)

           {

           System.out.println("INVALID ENTRY:");

    return;

           }

           str=new String[n];

           for(i=0;i<n;i++)

           {

           System.out.println("Enter sentence (ends with full stop):");

           s=input();

           if(s.charAt(s.length()-1)!='.')

           {

           System.out.println("Full stop at the end is mandatory:");

           i--;

         continue;

           }

           str[i]=s;

           }

           for(i=0;i< n;i++)

           {

                s=str[i];

                if(i%2==0)

                encrypt(s);

                else

                reverse(s);

           }

     }

     void encrypt(String s)

     {

           int i,len;

           char ch;

           String st="";

           len=s.length();

           for(i=0;i< len;i++)

           {

           ch=s.charAt(i);

           if((ch>=65 && ch<=90)||(ch>=97 && ch<=122))

           {

                     ch=(char)(ch+2);

                     if(ch >90 && ch< 97)

                     {

                           ch=(char)((64+ch-90));

                     }

                     else if(ch >122)

                     {

                          ch=(char)((96+ch-122));

                     }

                }

                st=st+ch;

           }

           System.out.println(st);

     }

     void reverse(String s)

     {

           int i;

           String s1;

           s=s.trim();

           s=s.substring(0,s.length()-1);

           while(true)

           {

                i=s.lastIndexOf(" ");

                if(i<0)

                break;

                s1=s.substring(i).trim();

                System.out.print(s1+ " ");

                 s=s.substring(0,i).trim();

           }

           System.out.println(s+".");

     }

     public static void main(String args[])

     {

           sentence ob=new sentence();

           ob.takeString();

     }

}