APIExample.java

public class APIExample {
    BoredActivitiesAPI sampleAPI;

    public APIExample(BoredActivitiesAPI boredActivitiesAPI) {
        this.sampleAPI = boredActivitiesAPI;
    }

    public Flowable<String> makeAPICall() {
        return sampleAPI.getFlowableResponse()
                  .onErrorReturn(new Function<Throwable, BoredActivities>() {
                            @Override
                            public BoredActivities apply(Throwable throwable) throws Exception {
                                BoredActivities boredActivities = new BoredActivities();
                                boredActivities.setLink("");
                                return boredActivities;           
                            }
                        })
                        .map(new Function<BoredActivities, String>() {
                            @Override
                            public String apply(BoredActivities boredActivities) throws Exception {
                                return boredActivities.getLink();
                            }
                        })
                        .subscribeOn(Schedulers.io()));
                .observeOn(AndroidSchedulers.mainThread());

    }

    public void updateUI() {

        makeAPICall().subscribe(new FlowableSubscriber<String>() {
            @Override
            public void onSubscribe(Subscription s) {

            }

            @Override
            public void onNext(String s) {
                // Result is received here for all the request we made here
            }

            @Override
            public void onError(Throwable t) {
                // Handle the error here
            }

            @Override
            public void onComplete() {

            }
        });

    }
}