349. intersection of two arrays

Input: nums1 = [1,2,2,1], nums2 = [2,2]
Output: [2]

Input: nums1 = [4,9,5], nums2 = [9,4,9,8,4]
Output: [9,4]

Each element in the result must be unique.
The result can be in any order.

public int[] intersection(int[] nums1, int[] nums2) {
    Set<Integer> set = new HashSet<>(), resSet = new HashSet<>();
    for (int num : nums1)
        set.add(num);
    for (int num : nums2)
        if (set.contains(num)) 
            resSet.add(num);


    int [] res = new int[resSet.size()];
    int i = 0;
    for (Integer num : resSet)
        res[i++] = num;

    return res;
}