Prime Numbers in Java - Algorithms

Question

I have started learning to code in Java and decided I would use the Project Euler site to give me little tasks to try and complete with each bit of new coding I learn. So I came

Answer 1

This is java version of this:

 static boolean isPrime(int n){
    if (n == 2) return true;
    if (n == 3) return true;
    if (n % 2 == 0) return false;
    if (n % 3 == 0) return false;

    int i = 5;
    int w = 2;
    while (i * i <= n) {
        if(n % i == 0)
        return false;

        i += w;
        w = 6 - w;
    }
    return true;
}

As it is described by @Alexandru: It's a variant of the classic O(sqrt(N)) algorithm. It uses the fact that a prime (except 2 and 3) is of form 6k-1 and 6k+1 and looks only at divisors of this form.