How to convert a List<Long> to Map<Long, Long> [duplicate]

Question

I have the below code and would like to use java 8 to convert a list of Long to a Map<Long,Long>.

Long globalVal= 10;
List<Long> queryLongs = Arrays.asList(600L,700L,800L);
Map<Long, Long> map = queryLongs.stream().collect(Collectors.toMap(i->i, globalVal)));

I get an error when I try to map the individual value in the list as the key of the map.

Answer 1

The second argument of toMap is also a Function, so you can't just pass globalVal.

Map<Long, Long> map = queryLongs.stream()
                                .collect(Collectors.toMap(Function.identity(), 
                                                          i->globalVal));