Multiple parallel api request using retrofit and rxjava Android

Question

I am new to Rx java and I have a scenario where I want to get data from multiple APIs. These APIs are independent of each other but I want to show data from these APIs in a View. So I want to make these APIs calls in such a manner so that I can get every API data at the same time. I already using retrofit 2. I know a little bit about RX JAVA, but I only know how to make one request at a time. Please help

Retorfit Rest Client:

public class RestClient {

    private static ApiService apiService = null;    
    public static ApiService getApiService(String url) {
        apiService = null;    
        HttpLoggingInterceptor interceptor = new HttpLoggingInterceptor();
        interceptor.setLevel(HttpLoggingInterceptor.Level.BODY);

        OkHttpClient okClient = new OkHttpClient.Builder().
                connectTimeout(1, TimeUnit.MINUTES).
                readTimeout(3, TimeUnit.MINUTES).
                addInterceptor(interceptor).build();    

        Gson gson = new GsonBuilder().setLenient().create();    

        Retrofit = new Retrofit.Builder()
                .baseUrl(url).client(okClient)
                .addConverterFactory(GsonConverterFactory.create(gson))
                .addCallAdapterFactory(RxJava2CallAdapterFactory.create())
                .build();

        apiService = restAdapter.create(ApiService.class);    
        return apiService;
    }
}

Api Service Interface:

public interface ApiService {


    @GET("v2/nearest_city")
    Observable<AqiDto> getAQI(@Query("lat") String latitude,
                          @Query("lon") String longitude,
                          @Query("key") String key);

    @GET("data/2.5/weather")
    Observable<WeatherDTO> getWeather(@Query("lat") String latitude,
                                  @Query("lon") String longitude,
                                  @Query("appid") String id);




}

Repository Class:

public class SiteListRepository {

    private static final String TAG = "SITE_LIST_REPO";
    private final CompositeDisposable disposable;
    private Context mContext;
    private AppUtilities mAppUtilities;

    public SiteListRepository(Application application) {
        mContext = application.getApplicationContext();
        disposable = new CompositeDisposable();
        mAppUtilities = new AppUtilities(mContext);
    }

public Object getData() {


    disposable = Observable.merge(RestClient.getApiService(BASE_URL_AIR_INDEX).getAQI(EcoHubApplication.mAppSharedPreference.getLatitude(), EcoHubApplication.mAppSharedPreference.getLongitude(), "2664b262-6369-415c-aa5a-ef2bd9ccf1cf")
            .subscribeOn(Schedulers.newThread()), RestClient.getApiService(BASE_URL_OPEN_WEATHER).getWeather(EcoHubApplication.mAppSharedPreference.getLatitude(), EcoHubApplication.mAppSharedPreference.getLongitude(), "b6907d289e10d714a6e88b30761fae22")
            .subscribeOn(Schedulers.newThread())).observeOn(AndroidSchedulers.mainThread()).subscribe(obj -> {

        object = obj;

    });



    return object;
}
}

Want to merge these 2 APIs calls together.

ViewModel:

public class SiteListViewModel extends AndroidViewModel {

    private SiteListRepository siteListRepository;
    public MutableLiveData<AqiDto> aqiDTOMutableLiveData = new MutableLiveData<>();
    public MutableLiveData<WeatherDTO> weatherDTOMutableLiveData = new MutableLiveData<>();
    private Object object;

    public SiteListViewModel(@NonNull Application application) {
        super(application);
        siteListRepository = new SiteListRepository(application);
    }

    public void getData(){
        object = siteListRepository.getData();

        if (object instanceof AqiDto){
            aqiDTOMutableLiveData.setValue((AqiDto) object);
        } else if (object instanceof WeatherDTO){
            weatherDTOMutableLiveData.setValue((WeatherDTO) object);
        }

    }

}

You can do either Single.zip(...) or Single.zipArray(...) — Christilyn Arjona
– Christilyn Arjona, Commented Dec 13, 2019 at 8:12
Zip is not the most effective way to manage it. I am looking out for a merge. — Kanwarpreet Singh
– Kanwarpreet Singh, Commented Dec 13, 2019 at 8:40
Then use Single.merge(...). Also, what do you mean by 'not the most effective way'? According to your usage, zip will be able to achieve what you want. — Christilyn Arjona
– Christilyn Arjona, Commented Dec 13, 2019 at 8:42
proandroiddev.com/… have a read, let me know I if am wrong. — Kanwarpreet Singh
– Kanwarpreet Singh, Commented Dec 13, 2019 at 9:19
In which part of the article does it say that zip is not effective? Because it seems to me that the article is praising its capabilities. — Christilyn Arjona
– Christilyn Arjona, Commented Dec 13, 2019 at 9:23

Sandeep dhiman · Accepted Answer · 2019-12-13 07:29:47Z

1

You can use Rxjava zip function for that

 @GET("v2/nearest_city")
    Observable<AqiDto> getAQI(@Query("lat") String latitude,
                          @Query("lon") String longitude,
                          @Query("key") String key);

    @GET("data/2.5/weather")
    Observable<WeatherDTO> getWeather(@Query("lat") String latitude,
                                  @Query("lon") String longitude,
                                  @Query("appid") String id);


    Observable.zip(ApiService.getAQI(your params),ApiService.getWeather(params)
    ,
    Function2<AqiDto, WeatherDTO,>> { 
        aqiDto, weatherDTO ->

        // Your operation here

        return weatherDTO;
    })
    .observeOn(AndroidSchedulers.mainThread())
    .doOnSubscribe { /* Loading Start */ }
    .doOnTerminate { /* Loading End */ }
    .subscribe(
            { /* Successfully Synced */ },
            { /* Having error */ }
    )

edited Dec 13, 2019 at 7:29

answered Dec 13, 2019 at 7:17

Sandeep dhiman

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1 Comment

Kanwarpreet Singh Over a year ago

Sir According to this document Zip is not the most effective way out: proandroiddev.com/…

Christilyn Arjona · Accepted Answer · 2019-12-16 08:05:16Z

1

Repository Class

public class SiteListRepository {

    private static final String TAG = "SITE_LIST_REPO";
    private final CompositeDisposable disposable;
    private Context mContext;
    private AppUtilities mAppUtilities;

    public SiteListRepository(Application application) {
        mContext = application.getApplicationContext();
        disposable = new CompositeDisposable();
        mAppUtilities = new AppUtilities(mContext);
    }

    public Observable getData() {
        return Observable.merge(RestClient.getApiService(BASE_URL_AIR_INDEX).getAQI(EcoHubApplication.mAppSharedPreference.getLatitude(), EcoHubApplication.mAppSharedPreference.getLongitude(), "2664b262-6369-415c-aa5a-ef2bd9ccf1cf")
            .subscribeOn(Schedulers.io()), RestClient.getApiService(BASE_URL_OPEN_WEATHER).getWeather(EcoHubApplication.mAppSharedPreference.getLatitude(), EcoHubApplication.mAppSharedPreference.getLongitude(), "b6907d289e10d714a6e88b30761fae22")
            .subscribeOn(Schedulers.io())).observeOn(AndroidSchedulers.mainThread())
    }
}

ViewModel

public class SiteListViewModel extends AndroidViewModel {

    private SiteListRepository siteListRepository;
    public MutableLiveData<AqiDto> aqiDTOMutableLiveData = new MutableLiveData<>();
    public MutableLiveData<WeatherDTO> weatherDTOMutableLiveData = new MutableLiveData<>();
    private Object object;
    private CompositeDisposable disposables = new CompositeDisposable();

    public SiteListViewModel(@NonNull Application application) {
        super(application);
        siteListRepository = new SiteListRepository(application);
    }

    public void getData(){
        disposables.add( 
            siteListRepository.getData()
                .subscribeOn(Schedulers.io())
                .observeOn(AndroidSchedulers.mainThread())
                .subscribe ( obj -> {
                     if (error != null) {
                         Log.e(TAG, error.message, error);
                     }
                     else {
                         if (obj instanceof AqiDto){
                             aqiDTOMutableLiveData.setValue((AqiDto) obj);
                         } else if (obj instanceof WeatherDTO){
                             weatherDTOMutableLiveData.setValue((WeatherDTO) obj);
                         }
                     }

                },
                error -> Log.e(TAG, error.message, error) // provide a second argument here to handle error
                )
        );


    }

@Override
protected void onCleared() {
    super.onCleared();
    disposable.clear();
    }
}

edited Dec 16, 2019 at 8:05

answered Dec 14, 2019 at 20:58

Christilyn Arjona

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3 Comments

Christilyn Arjona Over a year ago

@KanwarpreetSingh I've edited my code to account for exceptions. You can also checkout this helpful link that I found for handling errors github.com/ReactiveX/RxJava/wiki/Error-Handling-Operators

Kanwarpreet Singh Over a year ago

Hi, Can you add code on how to handle exception for the same? If the response of any of APIs is not coming.

Kanwarpreet Singh Over a year ago

I don't understand where you have declared an error.

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