Merging two Map with Java 8 Stream API

Question

I have two (or more) Map objects. I\'d like to merge them with Java 8 Stream API in a way that values for common keys should be the maxim

Answer 1

I added my contribution to the proton pack library which contains utility methods for the Stream API. Here's how you could achieve what you want:

Map mx = MapStream.ofMaps(m1, m2).mergeKeys(Integer::max).collect();

Basically mergeKeys will collect the key-value pairs in a new map (providing a merge function is optional, you'll end up with a Map> otherwise) and recall stream() on the entrySet() to get a new MapStream. Then use collect() to get the resulting map.