Stream of maps to map

Question

How can I flatten a Stream of Maps (of the same types) to a single Map in Java 8?

Map<String, Long> toMap(Stream<Map<String, Long>> stream) {     return stream. ??? } 

Answer 1

My syntax may be a bit off, but flatMap should do most of the work for you :

Map<String, Long> toMap(Stream<Map<String, Long>> stream) {     return stream.flatMap (map -> map.entrySet().stream()) // this would create a flattened                                                            // Stream of all the map entries                  .collect(Collectors.toMap(e -> e.getKey(),                                            e -> e.getValue())); // this should collect                                                                // them to a single map }