Article: The OOP has been explained wrongly to you - solution

WashingController.java

class WashingController {
    private final WashingService washingService;

    WashingController(WashingService washingService) {
        this.washingService = washingService;
    }

    void washWool() {
        Collection<LaundryElement> laundry = getAllLaundry().stream()
            .filter(WoolLaundryElement.class::isInstance).collect(toList());
        WashingMachine washingMachine = new WashingMachine();
        Integer spinSpeed = getRequestedSpinSpeed();
        Integer temperature = getRequestedTemperature();
        washingService.washWool(washingMachine, laundry, spinSpeed, temperature);
    }

    void washCotton() {
        Collection<LaundryElement> laundry = getAllLaundry().stream()
            .filter(CottonLaundryElement.class::isInstance).collect(toList());
        WashingMachine washingMachine = new WashingMachine();
        Integer spinSpeed = getRequestedSpinSpeed();
        Integer temperature = getRequestedTemperature();
        washingService.washCotton(washingMachine, laundry, spinSpeed, temperature);
    }

    void washSilk() {
        Collection<LaundryElement> laundry = getAllLaundry().stream()
            .filter(SilkLaundryElement.class::isInstance).collect(toList());
        WashingMachine washingMachine = new WashingMachine();
        Integer spinSpeed = getRequestedSpinSpeed();
        Integer temperature = getRequestedTemperature();
        washingService.washSilk(washingMachine, laundry, spinSpeed, temperature);
    }

    private Collection<LaundryElement> getAllLaundry() {
        Collection<LaundryElement> allLaundry = new ArrayList<>();
        // fill the allLaundry collection with available laundry by any way, 
        // e.g. obtaining it from repositories, providers, services
        return allLaundry;
    }

    private Integer getRequestedSpinSpeed() {
        return new Random().nextInt(1200);
    }

    private Integer getRequestedTemperature() {
        return new Random().nextInt(95);
    }
}