How to return an Object in a method when RxJava finishes running?

Question

Java

Good
There is a method, it should get an Object when Rxjava finishes, but I don’t know how to do it right, now I get a NullPointerException when calling.
Observable requests data from BD in io thread, Observer creates an instance of the class in the main thread - it all works. But how to wait for the method to wait for the completion of the request to the database, and not return null
here is an abridged excerpt

private DataTransferAddProduct addProduct;

    @Override
    public DataTransferAddProduct loadFromDB(int id_product) {

        Observable.create(observableEmitter -> {
        // тут происходит запрос
        }).subscribeOn(Schedulers.io())
                .observeOn(JavaFxScheduler.platform())
                .subscribe(o -> {
                    addProduct = (DataTransferAddProduct) o;
                });
/**return срабатывает до того, как  вызовется -  addProduct = (DataTransferAddProduct) o; */
        return addProduct; 
    }

Answer 1

Well, you can call toBlocking(), but this is fundamentally wrong. Return further Observables, otherwise what for there in general rx?