How to sort a Java ArrayList in Descending Order?

Question

I have to sort out 15 numbers that are given by a user in descending order. I can write how to sort them in ascending order but I don't know how to turn them. To use for-loop or something else?

Answer 1

If you use Java 8 or above you can use this:

yourList.sort(Comparator.reverseOrder());

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If you want to keep the initial ordering of the list, you can:

1. create a copy:

   List<YourType> copy = new ArrayList<>(yourList);
   

   And then sort the copy.

2. use streams:

   List<YourType> sorted = yourList.stream()
                                   .sorted(Comparator.reverseOrder())
                                   .collect(Collectors.toList());
   

Answer 2

You can use that example

List<Integer> list = Arrays.asList(10, 5, 7, 8, 6, 9);
Collections.sort(list, Collections.reverseOrder());
System.out.println(list);

Show: 10, 9, 8, 7, 6, 5

Answer 3

Sort the arraylist first then reverse it, like this:

Collections.sort(arraylist);
Collections.reverse(arraylist);
System.out.println(arraylist);

Answer 4

You can just call Comparator.reverseOrder() for that.