CODEWITHSUNDEEP
rx-java
FinalFive
FinalFive

Reputation: 1485

Better RxJava usage

I'm still learning RxJava and I wanted to know if there was another way to do what I want.

I have the following code, and it works:

apiManager.getChannelListByRegion(region)
            .observeOn(scheduler)
            .map(new Func1<ChannelList, List<ChannelList.Channel>>() {
                @Override
                public List<ChannelList.Channel> call(ChannelList channelList) {

                    if (params.getGenre() == 0) {
                        return channelList.getChannels();
                    } else {
                        List<ChannelList.Channel> filteredList = new ArrayList<>();
                        for (ChannelList.Channel channel : channelList.getChannels()) {
                            if (Integer.parseInt(channel.getGenreId()) == params.getGenre())
                                filteredList.add(channel);
                        }
                        return filteredList;
                    }
                }
            })
            .subscribe(new SuccessCallback<>(callback), new ErrorCallback(callback));

Some explanantion - The ChannelList is a POJO representing some JSon from an external service. I have no control over the structure of this JSon.

ChannelList contains an embedded List which I want and I am able to get it via the map() operator quite easily assuming no filtering of the list.

If I need to filter however, I resorted to a loop over its contents and checked for the filtering condition.

Is there a way to better filter? I'm assuming I would need to create another Observable that emits the List contents and provide a function but I'm not sure how to do that.

Upvotes: 0

Views: 129

Answers (1)

Marek Hawrylczak
Marek Hawrylczak

Reputation: 2504

I can show you how to rewrite your code using only FP and reactivex. It is rather matter of taste if it is simpler. I will use lambdas to make the code simpler to understand.

apiManager.getChannelListByRegion(region)
                .observeOn(scheduler)
                .flatMap(channelList->Observable.from(channelList.getChannels()))
                .filter(channel->params.getGenre() == 0 || Integer.parseInt(channel.getGenreId()) == params.getGenre())
                .toList()
                .subscribe(new SuccessCallback<>(callback), new ErrorCallback(callback));

As you can see, I first convert ChannelList into Observable of Channel, to later filter it and collect as list.

Upvotes: 1

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