Prime number calculation fun

Question

We\'re having a bit of fun here at work. It all started with one of the guys setting up a Hackintosh and we were wondering whether it was faster than a Windows Box of (nearl

Answer 1

You should be able to make the inner loop twice as fast by only evaluating the odd numbers. Not sure if this is valid Java, I'm used to C++, but I'm sure it can be adapted.

            if (current != 2 && current % 2 == 0)
                    prime = false;
            else {
                    for (int i = 3; i < top; i+=2) {
                            if (current % i == 0) {
                                    prime = false;
                                    break;
                            }
                    }
            }