Should I use LinkedHashMap or TreeMap if I insert and access in order?

Question

If i put and iterate in natural order, should I use LinkedHashMap or TreeMap?

I will use a Map<int, MyObj>, and I will put them in natural order (1,2,3,...). I know about their big-O time performances, but I also know that this is a borderline use.

[This answer](https://stackoverflow.com/a/17708526/17487348) should tell you everything you need to know. The question is which order you want to preserve. Natural order or insertion order? — Mushroomator, Apr 20 '22 at 17:16
If you insert and access in order, why aren't you using a List? — that other guy, Apr 20 '22 at 17:19
@Mushroomator I wrote that natural order and insertion order will be the same, also I already have seen that answer, but it did not help me. — albertopasqualetto, Apr 20 '22 at 21:25

score 2 · Accepted Answer · answered Apr 20 '22 at 17:19

2

Use a TreeMap. Not for any performance reasons, but because it can be assigned to SortedMap (or NavigableMap), and that communicates clearly your intent that the map has a defined order.

answered Apr 20 '22 at 17:19

erickson

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score 1 · Answer 2 · answered Apr 20 '22 at 18:48

If you want to keep the entries in the order in which you originally insert them, use LinkedHashMap.
If you want the entries kept in a sorted order, use a NavigableMap, the successor to SortedMap. Java comes with two such implementations: TreeMap and ConcurrentHashMap. The latter is thread-safe.

The sorted maps by default use natural order. Optionally, you can provide a Comparator to use for sorting. This has been covered many times already on Stack Overflow, so search to learn more.

Should I use LinkedHashMap or TreeMap if I insert and access in order?

2 Answers2