How to swap keys and values in a Map elegantly

Question

I already know how to do it the hard way and got it working - iterating over entries and swapping \"manually\". But i wonder if, like so many tasks, this one can be solved

Answer 1

Map<String, Integer> map = new HashMap<>();
Map<Integer, String> swapped = map.entrySet().stream().collect(Collectors.toMap(Map.Entry::getValue, Map.Entry::getKey));

Answer 2

If you had access to apache commons-collections, you could have used MapUtils.invertMap.

Note: The behaviour in case of duplicated values is undefined.

(Replying to this as this is the first google result for "java invert map").