What sorting algorithm used while overriding compare method of comparator interface?

Question

 Collections.sort(ar, new Comparator() {
                      @Override
                        public int compare(Intervals o1, Intervals o2) {            


        

Answer 1

The Comparator and Comparable interface don't do any sorting, so there is no sorting algorithm there. They just compare two Objects, something you need if you want to sort a list of those objects.