Prime Number in Java

A prime number is a natural number greater than 1, and that is divisible only by 1 and itself. Below is a Java program to check if a number is a prime number:

import java.io.*;
class PrimeNumber{
public static void main(String args[])throws IOException{
InputStreamReader isr=new InputStreamReader(System.in);
BufferedReader br=new BufferedReader(isr);
int num, i, fact=0;
System.out.print("Enter a number:");
num=Integer.parseInt(br.readLine());
for(i=1;i<=num;i++){
if(n%i==0)
fact++;
}
if(fact==2 && num!=1)
System.out.println(num+" is a prime number.");
else
System.out.println(num+" is not a prime number.");
}
}