使用java 8 Stream创建geojson特征集合

Question

这是我编写的用于将List转换为表示geojson FeatureCollection的ObjectNode的函数。

public class ToObjectNodeFunction implements Function<List<JsonNode>, ObjectNode> {

    @Override
    public ObjectNode apply(List<JsonNode> list) {
        /*
         * toGeojson() method return an ObjectNode representing that particular geometry
         */
        List<ObjectNode> objectNodes = list.parallelStream()
                .map(jsonNode -> {
                    String id = jsonNode.get("id").asText();
                    JsonNode tags = jsonNode.get("tags");
                    switch (jsonNode.get("type").asText()) {
                        case "node":
                            return new Point(jsonNode.get("lat").asDouble(), jsonNode.get("lon").asDouble(), id, tags).toGeojson();
                        case "way":
                            ArrayList<Point> points = new ArrayList<>();
                            JsonNode nodeList = jsonNode.get("geometry");
                            for (int j = 0; j < nodeList.size(); j++) {
                                JsonNode wayNode = nodeList.get(j);
                                points.add(j, new Point(wayNode.get("lat").asDouble(), wayNode.get("lon").asDouble()));
                            }
                            if (Polygon.isPolygon(points, tags)) {
                                return new Polygon(points, id, tags).toGeojson();
                            } else {
                                return new LineString(points, id, tags).toGeojson();
                            }
                        default:
                            Iterator<JsonNode> iterator = jsonNode.get("members").getElements();
                            List<List<Point>> rings = new ArrayList<>();
                            List<Point> ring;
                            while (iterator.hasNext()) {
                                JsonNode member = iterator.next();
                                JsonNode geometry = member.get("geometry");
                                ring = new ArrayList<>();
                                for (int ringIndex = 0; ringIndex < geometry.size(); ringIndex++) {
                                    JsonNode coordinates = geometry.get(ringIndex);
                                    ring.add(new Point(coordinates.get("lat").asDouble(), coordinates.get("lon").asDouble()));
                                }
                                rings.add(ring);
                            }
                            return new Multipolygon(Polygon.buildPolygons(rings), id, tags).toGeojson();
                    }
                })
                .collect(toList());

        ObjectNode featureCollection = NewFeatureCollection.createNewFeatureCollection();
        ArrayNode features = featureCollection.putArray("features");
        objectNodes.stream().forEach((objectNode) -> features.add(objectNode));

        return featureCollection;
    }
}

这种方法应该尽可能快，我想知道是否有更好的方法来实现结果。特别是，我想避免必须创建ObjectNode列表，然后必须迭代以创建表示要素集合的ObjectNode。如何直接创建要素集？