Removing null values from a Guava SetMultimap?

Question

If I have a SetMultimap like the following:

SetMultimap<String, MyObject> map = HashMultimap.create();
map.put("a", new MyObject());
map.put("a", null);
map.put("b", null);

What is the best way to remove the null values from this collection, so that I end up with something like (i.e. some keys will have only null values, but I still want the key):

   a -> obj
   b -> empty

Answer 1

Multimap<String, String> filteredMap = Multimaps.filterValues(map, Predicates.notNull());