LeetCode 412. Fizz Buzz

class Solution {
    public List<String> fizzBuzz(int n) {
        ArrayList<String> al = new ArrayList<>(n);
        al.clear();
        for(int i=1; i<=n; i++){
            boolean divisible3 = i%3==0;
            boolean divisible5 = i%5==0;
            String str="";
            if(divisible3) {
                str+="Fizz";
            } 
            if(divisible5) {
                str+="Buzz";
            } 
            if(str.isEmpty()) {
                str += String.valueOf(i);
            }
            al.add(str);
        }
        return al;
    }
}