zip rxjava operator cannot resolve method subscribe

Question

I want to send multiple requests over the network and this tutorial helped but i'm stuck at the latter part . seems i'm expected to return a value(OrderValues) from onSubscribe,onNext,.... since apply function returns a value. But ....,onNext returns void by default. Any help?Here is my piece of code

Observable<Restaurant> orderRestaurant= IdentityClient.getAPIService()
        .getRestaurantById(restaurantId)
        .subscribeOn(Schedulers.newThread())
        .observeOn(AndroidSchedulers.mainThread());

    Observable<Menu> orderMenu= IdentityClient.getAPIService()
        .getMenuById(menuId)
        .subscribeOn(Schedulers.newThread())
        .observeOn(AndroidSchedulers.mainThread());

    Observable<User> orderUser= IdentityClient.getAPIService()
        .getUserById(userId)
        .subscribeOn(Schedulers.newThread())
        .observeOn(AndroidSchedulers.mainThread());

    Observable<OrderValues> combineValues=Observable.zip(orderRestaurant, 
    orderMenu, orderUser,
       new Function3<Restaurant, Menu, User, OrderValues>() {
   @Override
   public OrderValues apply(Restaurant restaurant, Menu menu, User user) 
    throws Exception {
       return new OrderValues(restaurant,menu,user);
   }
I get an error here "cannot resolve method 'subscribe anonymous 
org.reactivestreams.Subscriber(....OrderValues)
   }).subscribe(new Subscriber<OrderValues>() {
   @Override
   public void onSubscribe(Subscription s) {

   }

   @Override
   public void onNext(OrderValues orderValues) {

   }

   @Override
   public void onError(Throwable t) {

   }

   @Override
   public void onComplete() {

   }
   });

Answer 1

I'm assuming that you are using RxJava 2.

Use Observer instead of Subscriber. And also do not assign the result to a new Observable (you called it combineValues).

private void myMethod() {
    Observable.zip(orderRestaurant, orderMenu, orderUser, new Function3<Restaurant, Menu, User, OrderValues>() {
                @Override
                public OrderValues apply(@NonNull Restaurant restaurant, @NonNull Menu menu, @NonNull User user) throws Exception {
                    return new OrderValues(restaurant, menu, user);
                }
            }).subscribe(new Observer<OrderValues>() {
                @Override
                public void onSubscribe(Disposable d) {

                }

                @Override
                public void onNext(OrderValues orderValues) {

                }

                @Override
                public void onError(Throwable e) {

                }

                @Override
                public void onComplete() {

                }
            });
        }
    }