覆盖比较器和 Collections.sort

Question

        Collections.sort(list, new Comparator<A>() {
        @Override
        public int compare(A a, A b) {
            return -a.getId().compareTo(b.getId());
        }
    });

If you put a minus in front of the return value in the comparator, will it correspond to reverseOrder method?

        Collections.sort(list, Collections.reverseOrder(new Comparator<A>() {
        @Override
        public int compare(A a, A b) {
            return a.getId().compareTo(b.getId());
        }
    }));

I mean, will it always work right?

Answer 1

-Integer.MIN_VALUE is also Integer.MIN_VALUE .

If you can guarantee that compareTo can't return Integer.MIN_VALUE , it will work the same (assuming the compareTo method is implemented correctly).

Otherwise, it would be safer to use the reverseOrder method, or to swap a and b in the expression (which is what reverseOrder does).