RxJava and Retrofit sample

api.java

public interface API {
    @GET("/user/{username}/dogs")
    Observable<Dog> getAllDogsOf(@Path("username") String username);

    @GET("/dog/{id}")
    Observable<Dog> getDogInfoById(@Path("id") int dogId);
}

rxJavaAndRetrofit.java

new RestService().getAllDogsOf("cesarferreira")
    .doOnSubscribe(() -> {  /* starting request */
        // TODO show Loading Spinner
    })
     .doOnCompleted(() -> { /* finished request */
        // TODO hide Loading Spinner
    })
    // request webservice for each dog id with all info
    .flatMap(dogId -> new RestService().getDogInfoById(dogId))
    .doOnError(throwable -> { 
        /* log the error */ 
    }) 
    .onErrorResumeNext(Observable.<~>empty())
    .subscribeOn(Schedulers.newThread())
    .observeOn(AndroidSchedulers.mainThread())
    .subscribe(dog -> {
        // TODO do what you want with the dog object
    });