APIExample.java

import androidx.lifecycle.LifecycleOwner;
import androidx.lifecycle.LiveData;
import androidx.lifecycle.LiveDataReactiveStreams;
import androidx.lifecycle.MediatorLiveData;
import androidx.lifecycle.Observer;

import com.toyaround.android.communities.questionsActivity.network.BoredActivities;
import com.toyaround.android.communities.questionsActivity.network.BoredActivitiesAPI;

import io.reactivex.functions.Function;
import io.reactivex.schedulers.Schedulers;

/**
 * Created by BalaKrishnan
 */
public class APIExample {
    BoredActivitiesAPI sampleAPI;
    LifecycleOwner lifecycleOwner;

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

    public LiveData<String> makeAPICall() {
        MediatorLiveData<String> linkData = new MediatorLiveData<>();

        LiveData<String> source = LiveDataReactiveStreams.fromPublisher(
                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()));

        linkData.addSource(source, new Observer<String>() {
            @Override
            public void onChanged(String responseResponseWrapper) {
                linkData.setValue(responseResponseWrapper);
                linkData.removeSource(source);
            }

        });
        
        return linkData;
    }

    public void updateUI() {
        makeAPICall().observe(lifecycleOwner, new Observer<String>() {
            @Override
            public void onChanged(String s) {

            }
        });
    }
}