Prime Number Detector

/**********************/
/* Prime Numbers      */
/* by Ron Marks       */
/*                    */
/* This program finds */
/* out if an integer  */
/* typed in is prime. */
/*                    */
/* Limitation:        */
/* Up to ~250,000     */
/**********************/

import java.util.Scanner;

public class Prime {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		boolean p;
		System.out.println("Type in a positive integer, 0 to exit:");
		while(true){
			int req = scan.nextInt();
			if(req == 0){
				System.out.println("Bye");
				break;
			}
			else{
				p = isPrime(req);
				if(p){
					System.out.println(req + " isn't a prime!");
				}
				else{
					System.out.println(req + " is prime!");
				}
				
			}
		}
	}
	
	public static boolean isPrime(int n){
		if(n == 1){
			return true;
		}
		int counter = 1;
		double a = 0.0;
		for(int i=2; i<=n/2; i++){
			for(int j = n - counter; j>1; j--){
				a = (i * j);
				if(a == n){
					return true;
				}
			}
			counter = 1;
		}
		return false;
	}                                                            
}