Guava ImmutableSortedSetMultimap?

Question

Google Guava has a SortedSetMultimap. Wonderful. Now where is the immutable version? There exists an ImmutableSetMultimap. But what about ImmutableSortedSetMultimap? (Please don't reply with "Why do you want one?")

Sir, elaborate some more on the topic. If I recall correctly, the nature of a set somewhat conflicts with ordering? — Caffeinated, Sep 10 '14 at 22:51
To answer the question, there indeed doesn't appear to be one, even though it's a perfectly reasonable thing to have. Maybe you should submit a feature request. — biziclop, Sep 10 '14 at 22:54

score 9 · Answer 1 · answered Sep 10 '14 at 23:15

9

It won't actually implement SortedSetMultimap, but ImmutableSetMultimap.Builder has an orderValuesBy(Comparator) method that you can use, which has the effect that the value collections are ImmutableSortedSets.

answered Sep 10 '14 at 23:15

Louis Wasserman

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score 2 · Answer 2 · answered Jan 17 '17 at 04:10

2

I was looking for this myself and just discovered this: Multimaps.unmodifiableSortedSetMultimap()

Not exactly what we're looking for, but good enough in my case.

answered Jan 17 '17 at 04:10

KevinT

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score 0 · Answer 3 · answered Sep 10 '14 at 23:09

If you don't need the supplementary meaning of Multimap, you have the indirect approach (I wrote the code in SO, so it might not work, but the idea is there):

SortedSetMultimap<K,V> set = ...;
ImmutableMap<K, ImmutableSortedSet<V>> result = ImmutableMap.copyOf(Maps.transform(set.asMap(), new Function<SortedSet<V>, ImmutableSortedSet<V>>() {
  public ImmutableSortedSet<V> apply(SortedSet<V> s) {
    return ImmutableSortedSet.copyOf(s);
  }
});

That is: turn your SortedSetMultimap into a Map<K,SortedSet<V>>, then a Map<K,ImmutableSortedSet<V>>, and then an ImmutableMap.

And I don't know enough Guava, but since the ImmutableSetMultimap is immutable, the ordering of copied set might remain: that would mean there is absolutely no need for a ImmutableSortedSetMultimap for navigation/iteration (apart if you require specific method of SortedSet).

Guava ImmutableSortedSetMultimap?

3 Answers3