Simple primality test

public static boolean prime (long n) {
  if ((n%2)==0) {
    if (n == 2 || n == 3) return true;
    return false;
  } else {
    for (int i = 3; i * i < n; i+=2){
      if ((n % i)==0) {
        return false;
      }
    }
  }
  return true;
}