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

问题

 Collections.sort(ar, new Comparator<Intervals>() {
                      @Override
                        public int compare(Intervals o1, Intervals o2) {                
                                return (Integer.valueOf(o1.getEnd()))
                                        .compareTo(Integer.valueOf(o2.getEnd()));
                        }
                    });

Hi all, I have the above code in java. Here, ar is a list and Intervals is a class with 2 integer variables : Start and End. I wanted to know what sorting algorithm is followed when we override the compare method of Comparator interface as above. I know, by default Collections.sort() and Arrays.sort() use Timsort algorithm. Any help will be appreciated. Thanks a lot in advance.

回答1:

Collections.sort() uses a variation of Timsort.

From the javadocs:

The implementation was adapted from Tim Peters's list sort for Python ( TimSort). It uses techiques from Peter McIlroy's "Optimistic Sorting and Information Theoretic Complexity", in Proceedings of the Fourth Annual ACM-SIAM Symposium on Discrete Algorithms, pp 467-474, January 1993.

Note that the Collections.sort() algorithms gets a "black box" comparator, and uses the value it yields for each compare - without caring what is going on behind the scenes of the comparator.

回答2:

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.

来源：https://stackoverflow.com/questions/30638617/what-sorting-algorithm-used-while-overriding-compare-method-of-comparator-interf