Best way to call web services?

public class AppNameApp extends Application {
private ApiService apiService;

@Override
public void onCreate() {
    super.onCreate();
}

public ApiService getApiService() {
    if (apiService == null) {
        apiService = 
provideRetrofit(ApiService.URL).create(ApiService.class);
    }
    return apiService;
}

private Retrofit provideRetrofit(String url) {
    return new Retrofit.Builder()
            .baseUrl(url)
            .client(provideOkHttpClient())
            .addConverterFactory(GsonConverterFactory.create(new Gson()))
            .build();
}

private OkHttpClient provideOkHttpClient() {
    OkHttpClient.Builder okhttpClientBuilder = new OkHttpClient.Builder();
    okhttpClientBuilder.connectTimeout(30, TimeUnit.SECONDS);
    okhttpClientBuilder.readTimeout(30, TimeUnit.SECONDS);
    okhttpClientBuilder.writeTimeout(30, TimeUnit.SECONDS);
    return okhttpClientBuilder.build();
}
}

public interface ApiService {
String URL = "https://api.example.com" + "/v1/";

@GET("accounts/{accountId}")
    Call<AccountInfo> getAccountInfo(@Path("accountId") String accountId);
}

public class HomeActivity extends AppCompatActivity{

@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_home);
}

private void getAccountInfo() {
 ((App) getApplication()).getApiService().getAccountInfo()
      .enqueue(new Callback<AccountInfo>() {
          @Override
          public void onResponse(Call<AccountInfo> call, 
   Response<AccountInfo> response) {
              if (response.isSuccessful()) {
                  // return to UI thread
                  // display AccountInfo on UI
              }
          }

          @Override
          public void onFailure(Call<AccountInfo> call, Throwable t) {
              // skip for now
          }
      });
 }
 }