How do I put sorted list into a HashMap in order?

Question

So I have this method here:

public Map<Long,Pkmn> sortByCreator(Map<Long,Pkmn> pkmns) {

        Collection<Pkmn> pkmn_to_get = pkmns.values();
        pkmns = null; //Delete useless memory.

        List<Pkmn> pkmn_to_sort = new LinkedList<Pkmn>();

        for(Pkmn pkmn : pkmn_to_get) {
            pkmn_to_sort.add(pkmn);
        }

        Collections.sort(pkmn_to_sort);

        Map<Long,Pkmn> return_map = new HashMap<Long,Pkmn>();

        for(Pkmn pkmn_data : pkmn_to_sort) {
            return_dex.put(pkmn_data.getId(), pkmn_data);
        }

        return return_dex;
    }

The problem is after Collections.sort(pkmn_to_sort) sorts the array; the for loop below adds they pkmn_data to the Map, but its un_sorted.

I know Map isn't like a stack where it goes in one after the other; but I want it to in this case.

Does anyone have a way of adding List items to a Map in the order of the List?

Thanks in advance :)

Note that this is not useful for anything at all: `pkmns = null; //Delete useless memory.` — Jesper, Jun 04 '20 at 16:23

Rogue · Answer 1 · 2020-06-04T16:41:24.157

1

HashMap is inherently unordered, try a LinkedHashMap to preserve the iteration order of the map relative to insertion.

edited Jun 04 '20 at 16:41

answered Jun 04 '20 at 16:23

Rogue

11,105
5
45
71

1

Or a TreeMap which will be sorted by the keys – David Zimmerman Jun 04 '20 at 16:41

How do I put sorted list into a HashMap in order?

1 Answers1