Converting a collection to Map by sorting it using java 8 streams

Question

I have a list that I need to custom sort and then convert to a map with its Id vs. name map.

Here is my code:

Map map = new Link         


        

Answer 1

You have Collectors.toMap for that purpose :

Map<Long, String> map = 
    list.stream()
        .sorted(Comparator.comparing(Building::getName))
        .collect(Collectors.toMap(Building::getId,Building::getName));

If you want to force the Map implementation that will be instantiated, use this :

Map<Long, String> map = 
    list.stream()
        .sorted(Comparator.comparing(Building::getName))
        .collect(Collectors.toMap(Building::getId,
                                  Building::getName,
                                  (v1,v2)->v1,
                                  LinkedHashMap::new));

Answer 2

Use toMap() of java.util.stream.Collectors