Prime number checker in java

import java.util.Scanner;
/**
 * @ Shaun B
 * @ v1.0.0.1
 * @ 2012-08-08
 */
public class primeNumber
{
    private static boolean run = true;
    private static int readNumber = 0;
    public static void main (String args [])
    {
        System.out.println ("Donkeysoft MMXII - this will determine whether or not\n"
                        +"the number you enter is a prime or even number. If you wish\n"
                        +"to leave this program, please type in -1 and press enter\n"
                        +"to exit.\n");
        Scanner keyboardBuffer = new Scanner (System.in);
        while (run)
        {
            System.out.println ("Please enter a whole (integer) number");
            System.out.print ("C:\\>");
            readNumber = keyboardBuffer.nextInt();
            if (readNumber%2 == 0)
            {
                System.out.println ("The integer that you entered is an even number");
            }
            else
            if ( (readNumber%2 != 0 && readNumber %3 != 0) || readNumber == 3)
            {
                System.out.println ("The integer that you entered is a prime number");
            }
            else
            {
                System.out.println ("The number is odd but not prime");
            }
            if (readNumber == -1 )
            {
                System.out.println("\n\nGood bye, have a nice day :-)");
                run = false;
            }
        }
        return;
    }
}