How to check prime number ?

1. public class PrimeNumberAlgorithm {
2. public static void main(String[] args) {
3. isPrimeNumber(11);
4. }
5. private static void isPrimeNumber(int n) {
6. boolean isPrime = true;
7. int m = n / 2;
8. for (int i = 2; i <= m; i++) {
9. if (n % i == 0) {
10. isPrime = false;
11. break;
12. }
13. }
14. System.out.println(isPrime == true ? "Prime number !!" : "Not prime number !!");
15. }
16. }

Output: Prime number !!

Time complexity is O(n/2)