Project Euler Problem 3 - does work

import java.util.ArrayList;
import java.util.Collections;

public class PESolver3
{
    public static void main(String[] args)
    {
        ArrayList<Long> factors = PESolver3.getFactors(Long.parseLong(args[0]));
        Collections.sort(factors, Collections.reverseOrder());
        if (factors != null) {
            for (Long factor : factors) {
                System.out.print(factor + ": ");
                if (PESolver3.isPrime(factor)) {
                    System.out.println("prime");
                } else {
                    System.out.println("not prime");
                }
            }
        }
    }

    public static ArrayList<Long> getFactors(long num)
    {
        if (num < 1) {
            return null;
        } else if (num == 1) {
            ArrayList<Long> factors = new ArrayList<Long>();
            factors.add(1L);
            return factors;
        }

        ArrayList<Long> factors = new ArrayList<Long>();
        Double tmpRoot = new Double(Math.ceil(Math.sqrt(num)));
        long root = tmpRoot.longValue();
        for (long x = 1L; x <= root; x++) {
            if (num % x == 0) {
                if (!factors.contains(x)) {
                    factors.add(x);
                }
                Long x2 = (long) (num / x);
                if (!factors.contains(x2)) {
                    factors.add(x2);
                }
            }
        }

        return factors;
    }

    public static boolean isPrime(long num)
    {
        if (num <= 1) {
            return false;
        } else if (num == 2) {
            return true;
        }
        Double tmpRoot = new Double(Math.ceil(Math.sqrt(num)));
        long root = tmpRoot.longValue();
        for (long x = 2; x <= root; x++) {
            if (num % x == 0) {
                return false;
            }
        }
        return true;
    }
}