This Java program encrypts strings by shifting letters 3 positions forward in the alphabet, wrapping around from z to c, and preserving spaces and other characters. The user inputs a string which is encrypted by shifting each character and storing it in a new array before outputting the encrypted string.

1. import java.util.Scanner;
public class Cipher
{
public static void main(String args[])
{
int len,i,ascii = 0;
char c;
Scanner sc = new Scanner(System.in);
System.out.println("enter string to encrypt");
String str = sc.nextLine();
len = str.length();
char s[] = new char[len];
for(i=0;i<len;i++)
{
c = str.charAt(i);
if(c >= 'a' && c<='w' || c >= 'A' && c <= 'W')
{
ascii = (int)c;
ascii = ascii + 3;
c = (char)ascii;
}
else
{
if(c == ' ')
c = ' ';
else if(c == 'x')
c = 'a';
else if(c == 'y')
c = 'b';
else if(c == 'z')
c = 'c';
else if(c == 'X')
c = 'A';
else if(c == 'Y')
c = 'B';
else if(c == 'Z')
c = 'C';
}
s[i] = new Character(c);
}
System.out.println("Encrypted String : ");
for(i=0;i<len;i++)
{
System.out.print(s[i]);
}
}
}