RxJava, Retrofit - changing the response into ArrayAdapter item object?

Question

I'm playing with RxJava in Android. I'm trying to get the response of places from the server. Everything works fine:

Here is my Retrofit interface:

@GET("/some/path")
Observable<Response> search(@QueryMap Map map);

Here is how I handle this:

    endpointService.search(requestMap)
            .onErrorReturn(throwable -> {
                L.e(TAG, "problems");
                return null;
            })
            .subscribe(rxBus::send);

As you may see, I post a event (RxBus) to interested parties, in this case, a fragment:

    rxBus.register(Response.class)
            .subscribe(event -> {
                L.d(TAG, "Received search response");
            });

For now it works. I'm not shure, this "idea" of handling REST calls won't finish in a disaster (I'm new into RxJava), but for now it looks allright...

Anyways - this response is huge. I only need a list of names and addresses. And this response gives me a huuuge JSON with a lot of additional data.

My idea is to change this with map (or flatMap, I still have problems with knowing the difference). I've implemented something like

    .map(event -> {
             List<SearchItem> list = new ArrayList<>();
             for (Response r : event.getItems) {
                  list.add(new Item(r.getName, r.getAddress));
              }
                 return list;
            }
         )

And it works, however I'm not sure if foreach-ing isn't a bit too "oldschool". IDE says that I cant use collect call however I've never used it, and the autocorrection makes things even worse :)

So - am I handling this whole thing in a right way?

EDIT:

I modified my code:

rxBus.register(Response.class)
            .subscribeOn(Schedulers.newThread())
            .observeOn(AndroidSchedulers.mainThread())
            .map(event -> event.getResponse().getList())
            .flatMap(Observable::from)
            .map(v -> new SearchItem(v.getName(), v.getAddress())
            .toList()
            .subscribe(event -> {
                L.w(TAG, "Stuff happens");
            });

I have no idea what happened, but this code no longer works. Well - kinda. Without .toList() it launches that Log a number of times. However with - nothing happens. Am I doing something wrong?

Answer 1

I think the general approach is fine. You can slightly improve the handling of items by something like:

...
.map(Event::getItems)
.flatMap(Observable::from)
.map(response -> new Item(response.getName(), response.getAddress()))
.toList()
...

I assume you use retrolambda. In this case what the IDE suggests ("collect") is to apply Java 8 Streams API syntax to the for-loop, which won't work in Android.

EDIT

I didn't realize the first option wouldn't work for the hot observable case that never emits onCompleted event, which is requiered by toList() operator to know when to stop assembling the list.

Thanks to @david.mihola, there's a different option for this case:

...
.flatMap(event -> Observable.from(event.getResponse().getList())
                            .map(item -> new SearchItem(v.getName(), v.getAddress()))
                            .toList())
...