Spring Boot: Dropdown options appear in random order

[candid widget]

Dropdowns map for sort dropdown options.

class Dropdowns {
  public final LinkedHashMap<String, String> orderMap = new LinkedHashMap<>(Map.of(
      "noviji", "Prvo najnoviji",
      "popularni", "Prvo najpopularniji",
      "skuplji", "Po ceni opadajuće",
      "jeftiniji", "Po ceni rastuće",
      "veći", "Po površini opadajuće",
      "manji", "Po površini rastuće"
  ));
}

list method calls listModel method which adds orderMap to the Model.

public class ListingController extends BaseController {
    private final Dropdowns dropdowns;
    // ...

    // Main
    @GetMapping("")
    public String list(Model model, Authentication auth,
        @RequestParam(name = "strana", defaultValue = "0", required = false) int pageNum,
        @RequestParam(name = "redosled", defaultValue = "noviji", required = false) String order) {
        // 4 Authentication & authorization
        Object user = currentUser(auth);

        Page<Listing> page = listingServ.findAll(pageNum, order);
        listModel(model, page, order);

        // 5 Security logging
        logger.info("User {} viewed all listings.", user);
        return "listings/listing_list";
    } // [1]

    private void listModel(Model model, Page<Listing> page, String order) {
        ListingSearchDTO searchDTO = new ListingSearchDTO();
        List<Listing> listings = page.getContent();

        model.addAttribute("orderMap", dropdowns.orderMap);
        model.addAttribute("order", order);
        model.addAttribute("page", page);
        model.addAttribute("searchDTO", searchDTO);
        model.addAttribute("listings", listings);
    } // [1]
}

1/2

[spiral mirage]

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[candid widget]

Sort dropdown:

<!-- Sort select -->
<form class="mb-3 w-50" method="get" novalidate th:fragment="sort">
  <th:block th:if="${searchDTO != null}">
    <input type="hidden" name="grad" th:value="${searchDTO.getCity()}">
    <input type="hidden" name="brojSoba" th:value="${searchDTO.getRoomCount()}">
    <input type="hidden" name="m2Od" th:value="${searchDTO.getM2From()}">
    <input type="hidden" name="m2Do" th:value="${searchDTO.getM2To()}">
    <input type="hidden" name="cenaOd" th:value="${searchDTO.getPriceFrom()}">
    <input type="hidden" name="cenaDo" th:value="${searchDTO.getPriceTo()}">
  </th:block>

  <select class="form-select" name="redosled" onchange="this.form.submit()">
    <option th:each="entry : ${orderMap}" th:value="${entry.key}" th:selected="${entry.key == order}">[[${entry.value}]]</option>
  </select>
</form>

Select options appear in incorrect order (not like it's in Dropdowns class).

[agile notch]

The problem is that Map.of() already is unsorted an will destroy the order. If you want to ensure the order, you need to add the key-value pairs one by one in the correct order to the LinkedHashMap.

Or I don't understand what your problem is. Not sure about that.

[candid widget]

The sort dropdown options do not appear in correct order. They should be in this order:

"noviji", "Prvo najnoviji",
"popularni", "Prvo najpopularniji",
"skuplji", "Po ceni opadajuće",
"jeftiniji", "Po ceni rastuće",
"veći", "Po površini opadajuće",
"manji", "Po površini rastuće"

So how do I initialize LinkedHashMap without adding entries one by one?

[spare swan]

First create a List of entries, then convert it to a LinkedHashMap

[agile notch]

Java should add a SequencedMap.of().

In olden days people did this with double brace initialisation:

public final LinkedHashMap<String, String> orderMap = new LinkedHashMap<>() {{
  put("noviji", "Prvo najnoviji");
  put("popularni", "Prvo najpopularniji");
  ...
}};

But this is frowned upon.

[spare swan]

it would probably be Map.sequencedMapOf/Map.sequencedOfEntries or something like that I think

because having static methods with the same name on subtypes is a bit confusing as recompiling changes behaviour with the same source code

and map factories are a bit odd anyway

Also that would probably be an immutable one, not a LinkedHashMap

you are free to write all 11 versions by yourself though

[agile notch]

Yeah, they'd need an additional implementation because currently they have this probing thing with the twice-as-big array. Whenever I need an immutable Map with strict insertion order, I use Guava ImmutableMap.

[spare swan]

I think Map.of even randomizes the order

https://docs.oracle.com/en/java/javase/25/docs/api/java.base/java/util/Collections.html#unmodifiableSequencedMap(java.util.SequencedMap) exists

but that's an unmodifiable view

whereas the question was about a mutable Map I think

[agile notch]

The question was why the order is destroyed at all.

[spiral mirage]

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[candid widget]

I did this, but it's kinda counter-intuitive.

public final LinkedHashMap<String, String> orderMap;

@Autowired
public Dropdowns(ItemService service) {
    itemList = service.findAll();

    this.orderMap = new LinkedHashMap<>();
    this.orderMap.put("noviji", "Prvo najnoviji");
    this.orderMap.put("popularni", "Prvo najpopularniji");
    this.orderMap.put("veći", "Po površini opadajuće");
    this.orderMap.put("manji", "Po površini rastuće");
    this.orderMap.put("skuplji", "Po ceni opadajuće");
    this.orderMap.put("jeftiniji", "Po ceni rastuće");
}

[spare swan]

alternatively

orderMap = Stream.of(Map.entry(...), Map.entry(...), ...)
    .collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue, (a,b)-> a, LinkedHashMap::new));

which means

• create a Stream of Map.Entrys (each with a key and value
• convert it to a Map
  • the key is the entry key
  • the value is the entry value
  • in case of duplicates, pick the first
  • create a LinkedHashMap for ordering