Implementing Rail Fence Cipher Transposition In Java:

import java.io.*;
public class railfencecipher
{
public void encrypt(String line,int rail)
{
System.out.println("Result:");
int shift=0,p=0,itr;
for(int i=0;i<rail;i++)
{
p=i;
if(i==0||i==rail-1)
shift=((rail-2)*2)+2;
itr=1;
while(p<line.length())
{
System.out.print(line.charAt(p));
if(i!=0&&i!=rail-1)
{
shift=((rail*itr-itr)-p)*2;
}
p+=shift;
itr++;
}
}
}
public void decrypt(String line,int arr[])
{
System.out.println("Result:");
int ptr[]=new int[arr.length+1];
int p1=0,p2=0,p3=0,c=1;
boolean chk=true;
System.out.print(line.charAt(ptr[p3]+p1));
ptr[p3]++;
while(c<line.length())
{
if(chk)
{
p1+=arr[p2];
p2++;
p3++;
}
else
{
p1-=arr[p2];
p2--;
p3--;
}
System.out.print(line.charAt(ptr[p3]+p1));
c++;
ptr[p3]++;
if(p2==arr.length)
{
p2--;
chk=false;
}
else if(p2==-1)
{
p2++;
chk=true;
}
}
}
public static void main(String args[])throws IOException
{
railfencecipher obj=new railfencecipher();
String line;
int rail,arr[],temp;
BufferedReader in=new BufferedReader(new InputStreamReader(System.in));
System.out.println("MENU:\n1) Encryption:\n2) Decryption:");
int choice=Integer.parseInt(in.readLine());
System.out.println("Enter the string:");
line=in.readLine();
System.out.println("Enter the no of rails:");
rail=Integer.parseInt(in.readLine());
switch(choice)
{
case 1:
temp=line.length()-rail;
int spaces;
if(temp%(rail-1)!=0)
{
spaces=(rail-1)-(temp%(rail-1));
if((temp/(rail-1))%2!=0)
{
spaces+=rail-1;
}
}
else
{
spaces=temp%(rail-1);
if((temp/(rail-1))%2==0)
{
spaces+=rail-1;
}
}
for(int g=0;g<spaces;g++)
line+=' ';
obj.encrypt(line,rail);
break;
case 2:
temp=line.length()-rail;
arr=new int[rail-1];
if((temp/(rail-1))%2==0)
arr[0]=1+(temp/(rail-1))/2;
else
arr[0]=1+((temp/(rail-1))+1)/2;
arr[1]=arr[0]*2-2;
for(int i=2;i<rail-1;i++)
arr[i]=arr[1];
obj.decrypt(line,arr);
break;
}
}
}