A controller that loads a shopping cart (think online shopping).

CartControllerImpl.java

/**
 * A controller that loads a shopping cart (think online shopping).
 */
public class CartControllerImpl implements CartController {

    final CartModel model;
    final TaxModel taxModel;
    final CurrencyUnit currencyUnit;
    final MoneyFormatter moneyFormatter;
    final RxBus rxBus;


    AtomicBoolean isLoading = new AtomicBoolean(false);

    public CartControllerImpl(
            CartModel model,
            TaxModel taxModel,
            CurrencyUnit currencyUnit,
            MoneyFormatter moneyFormatter,
            RxBus rxBus
    ) {
        this.model = model;
        this.taxModel = taxModel;
        this.currencyUnit = currencyUnit;
        this.moneyFormatter = moneyFormatter;
        this.rxBus = rxBus;
    }

    @Override
    public void load() {
        //prevent repeating load calls when data is already loading
        if (!isLoading.get()) {
            isLoading.set(true);


            model.getCart()
                    .withLatestFrom(taxModel.getTaxRate(), (entity, taxRate) ->
                            new Cart(
                                    entity,
                                    model,
                                    currencyUnit,
                                    moneyFormatter,
                                    taxRate
                            )
                    )
                    .subscribe(new Subscriber<Cart>() {
                        @Override
                        public void onCompleted() {
                            isLoading.set(false);
                        }

                        @Override
                        public void onError(Throwable e) {
                            Timber.e(e, "Error loading cart");
                            isLoading.set(false);
                        }


                        @Override
                        public void onNext(Cart cart) {
                            rxBus.send(new CartLoadedEvent(cart));
                        }
                    });
        }
    }
}