Jewels and Stones

class Solution {
    public int numJewelsInStones(String J, String S) {
        int res = 0;
        for (char j : J.toCharArray()) {
            for (char s : S.toCharArray()) {
                if (s == j) {
                   res ++;
                }
            }
        }        
        
        return res;
    }
}