rsa algorithm

[nimmo]

as i m working on implementation of rsa algorithm,and during maiking console of it i found an error int cannot be dereferenced and i m unable to solve it because of working on java first tym...help me here is my code

import java.lang.*;
import java.math.*;
import java.util.*;
class rsa
 {
   int p,q,n,g,d,k,m;
    int e=1;
    int ct,pt;
    int number()
    {
       Scanner in = new Scanner(System.in);
      System.out.println("enter the prime value ");
      p = in.nextInt();
      int flag = 1;
      for(int i=2;i<p;i++)
        { 
         if(p%i==0) 
          { 
        System.out.println(p+" is not a Prime Number"); 
        flag = 0; 
        break; 
          } 
        } 

         if(flag==1) 
        {
            System.out.println(p+" is a Prime Number"); 
            return p;
        }

        else 
         return 0; 
}        
/***********************************************************************/
void calculate(int x,int y)
{
        p=x;
        q=y;
        int count =0;
       try
        {
         int i;
        n = p*q;
        System.out.println("value of n :"+n);
        g=(p-1)*(q-1);
        System.out.println("value of g :"+g);
        }
       catch(Exception e)
        {
        System.out.println("error"+e.getMessage());
        }
}
/************************************************************************/


/***********************************************************************/

    int formula()
        {

        //(d*e) mod g = 1;
         d =  e.modInverse(g)  ;
         System.out.println("value of d "+d);

          System.out.println("Encryption process started:");
          Scanner scan = new Scanner(System.in);
         System.out.println("enter the  assumed value of plain text:");
         pt= scan.nextInt();
         ct = pt^e % n;
         System.out.println(""+ct);
         System.out.println("cipher text ct is send to receiver:");
         System.out.println("Decryption process started:");
         pt = ct^d%n;
        System.out.println(""+pt);
        System.out.println("this is original palintext ,process completed thanku");

        return 0;
        }

 }
class rsa061
{
  public static void main(String args[])
   {    int p=0,q=0;
    int m;
    rsa r = new rsa();
    do
    {
     p= r.number();

    }
    while(p==0);


    do
    {
     q= r.number();

    }
    while(q==0);


    r.calculate(p,q);

    //n and g

    for(int i=r.g; i>2; i--)
    {
        BigInteger b1 = new BigInteger(""+i); // there's a better way to do this. I forget.
            BigInteger b2 = new BigInteger(""+r.g);
        BigInteger gcd = b1.gcd(b2);
            int c = gcd.intValue();
        if(c==1)
        {
            r.e = i;
            System.out.println("E = " + r.e);
            break;
        }

    }


    r.formula();
   }
}

[Taywin]

Line 9, you cannot declare an int as a method/function. Simply implement another method in your rsa class and name it something like getPrimeNumberFromUser() and return a prime number if the number entered by the user is valid. In other words, reimplement lines 9~33 in a method.

Suggestions:
1) Your prime checker should go up to square root of the number itself (use Math.sqrt). It will speed up your method by a LOT.
2) You must not allow p and q to be the same number.
3) I don't really see the purpose of having p and q as rsa member variables...