Level 41

São Paulo

20.08.2020
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10comments

no idea how to do last 4 conditions. HELP PLEASE

Question about the task

Restaurant (part 14)

Java Multithreading, Level 9, Lesson 15

Under discussion

i really don't understand

1. Create a void put(EventDataRow data) method in StatisticsStorage.

2. To allow the put(EventDataRow data) method to add the data object to the map, we need the event type (EventType).
It would make sense for the event to store its type. Therefore,
2.1. Add an EventType getType() method to the EventDataRow interface
2.2. Implement this method in each event class: OrderReadyEventDataRow, NoVideosAvailableEventDataRow, VideosSelectedEventDataRow

3. Make it so that the void put(EventDataRow data) method cannot be accessed outside the StatisticsManager class.
Take advantage of the features of nested classes.

Now it remains to arrange StatisticsManager calls in places that generate events.

4. Record an event for the cook when the food is prepared.
Add a getter for the dishes field to the Order class, and use it when creating the event.

5. Record a "videos selected" event before displaying ads to the customer.

6. The record method with one EventDataRow parameter should record the event in statisticsStorage.

Requirements:

The EventDataRow interface should declare an EventType getType() method.
Classes that support the EventDataRow interface must correctly implement the getType() method.
When the food is prepared, the cook must generate an appropriate event.
Before a video is displayed, a "videos selected" event must be recorded.
The StatisticsStorage class's put method must be implemented in accordance with the task conditions.
The StatisticsManager class's record method with one EventDataRow parameter should record the passed event in statisticsStorage.

package com.codegym.task.task27.task2712; import com.codegym.task.task27.task2712.kitchen.Cook; import com.codegym.task.task27.task2712.kitchen.Waiter; import java.io.IOException; public class Restaurant { public static void main(String[] args) throws IOException { Tablet tablet1 = new Tablet(1); Cook cook = new Cook("Mito"); tablet1.addObserver(cook); Waiter waiter = new Waiter(); cook.addObserver(waiter); tablet1.createOrder(); } }

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Andrei

Level 41

26 May 2021, 08:42

This is one of the weakest tasks of this Big Task so far, they just leave you hanging. Good thing now there is the validator which shows you the correct solution. I can't imagine how I would have managed without this validator.

Guadalupe Gagnon

Level 37 , Tampa, United States

20 August 2020, 20:35

Start with the cook class: You will want to pass the appropriate EventDataRow object to the record (OrderReadyEventDataRow). Look at the constructor for this class and pass it all the proper arguments when creating the new object. Use that hint to figure out what to do before a video is displayed. In the StatisticsStorage class there is a map that stores lists based on EventType keys. You just added a getType() method to the EventDataRow interface and implemented it in the classes that support this interface. You can pull the proper list with the key from the getType() method of the variable "data" then add that object to the list:

storage.get(data.getType()).add(data);

Make sure you call the proper method in the record method of the StatisticsManager class

Henrique

Level 41 , São Paulo, Brazil

20 August 2020, 21:15

Thanks for your answer, Guadalupe. I'm trying, but it's been really hard to understand. 1) Is the update method in Cook class the right place to create the new object? I tried things like this, and it didn't work:

StatisticsManager.getInstance().record(new OrderReadyEventDataRow(Tablet.class.getName(), this.name, order.getTotalCookingTime(), order.getDishes()));

2) Is the processVideos method (in AdvertisementManager class) the right place to deal with this video thing? I tried things like this and it also didn't work:

StatisticsManager.getInstance().record(new VideosSelectedEventDataRow(playlist, playlist.size(), timeSeconds));
ConsoleHelper.writeMessage("videos selected");

3) What do you mean by "pull the proper list..."? I interpreted that I have to assign something to the variable "statisticsStorage" in the record method in StatisticsManager class. Is that correct? Anyway, I still don't have a clue of what to put inside the put method and the record method.

Guadalupe Gagnon

Level 37 , Tampa, United States

20 August 2020, 22:03

Its been awhile since I did this task, and i don't have my original code, but here goes: 1) Looking at the Restaurant class, the cook is set as an observer of the tablet. Moving to the Tablet class, line 27 is where the order is passed to the observer (cook). Now moving to the cook class, in the Update method there are 2 arguments that are passed in, 'observable' and 'arg'. You are using 'arg' as part of the code, however 'observable' is not being used. I bet this is the tablet name to pass in as the first argument of the new OrderReadyEventDataRow.

Guadalupe Gagnon

Level 37 , Tampa, United States

20 August 2020, 22:13

2) I would guess that the best place to add that line is after "videos selected" and before "Displaying" (in between lines 43-44). The second argument of the VideosSelectedEventDataRow constructor is "Amount", this might be the total amount of $$ displaying all the adds in the list will generate (add all the amountPerImpressions up in the selected list). 3) The line that I gave you "should" be the correct line for the put method. Call the put method from the record method of the StatisticsManager class.

Henrique

Level 41 , São Paulo, Brazil

20 August 2020, 22:31

1) Before you said, I already had tried to pass the "observable" (with a toString), but it didn't work as well. Like this: Cook class:

@Override
public void update(Observable observable, Object arg) {
    Order order = (Order) arg;
    ConsoleHelper.writeMessage("Start cooking - " + arg + ", cooking time " + order.getTotalCookingTime() + " min");
    setChanged();
    notifyObservers(arg);

    StatisticsManager.getInstance().record(new OrderReadyEventDataRow(observable.toString(), this.name, order.getTotalCookingTime(), order.getDishes()));
}

Henrique

Level 41 , São Paulo, Brazil

20 August 2020, 22:32

2) I also placed that line where you suggested, but I didn't understand where should I place the "amountPerImpression" and how should I do it. So I tried entering a random number and it didn't work as well:

public void processVideos() {
    if(storage.list().isEmpty())
        throw new NoVideoAvailableException();

    List<Advertisement> remainingList = new ArrayList<>(storage.list());
    getOptimalPlaylist(remainingList, new ArrayList<>(), timeSeconds);

    if(playlist.isEmpty())
        throw new NoVideoAvailableException();

    Collections.sort(playlist, new Comparator<Advertisement>() {
        @Override
        public int compare(Advertisement o1, Advertisement o2) {
            if(o2.getAmountPerImpression() > o1.getAmountPerImpression())
                return 1;
            else if(o2.getAmountPerImpression() == o1.getAmountPerImpression()) {
                long ApIpSecondObj1 = o1.getAmountPerImpression() / o1.getDuration();
                long ApIpSecondObj2 = o2.getAmountPerImpression() / o2.getDuration();
                return (int) (ApIpSecondObj1 - ApIpSecondObj2);
            }
            return -1;
        }
    });
    playlist.forEach(Advertisement::revalidate);
    ConsoleHelper.writeMessage("videos selected");
    StatisticsManager.getInstance().record(new VideosSelectedEventDataRow(playlist, 800, timeSeconds));
    playlist.forEach(video -> ConsoleHelper.writeMessage("Displaying " + video.getName() + "... " + video.getAmountPerImpression() + ", " + (1000L * video.getAmountPerImpression() / video.getDuration())));
}

Henrique

Level 41 , São Paulo, Brazil

20 August 2020, 22:33

And now my "put" and "record" methods are like this. Do you think it's correct?

public class StatisticsManager {
    private static StatisticsManager instance = null;
    private StatisticsStorage statisticsStorage = new StatisticsStorage();

    private StatisticsManager() {
    }

    public static StatisticsManager getInstance() {
        if(instance == null)
            instance = new StatisticsManager();
        return instance;
    }

    public void record(EventDataRow data) {
        StatisticsStorage ss = new StatisticsStorage();
        ss.put(data);
    }

    protected class StatisticsStorage {
        Map<EventType, List<EventDataRow>> storage;

        public StatisticsStorage() {
            storage = new HashMap<EventType, List<EventDataRow>>();

            for(EventType eventType : EventType.values())
                storage.put(eventType, new ArrayList<EventDataRow>());
        }

        protected void put(EventDataRow data) {
            storage.get(data.getType()).add(data);
        }
    }
}

Henrique

Level 41 , São Paulo, Brazil

20 August 2020, 22:38

Sorry for asking you everything and treating you like a "mentor". But I'm very frustrated cause it seems that, from everyone that did this course until here, I am the only one who cannot even understand this task, so I'm really desperate do just pass this and unlock the next tasks, so I can move on with my life. And the validator doesn't even give a hint or suggest where should I look to solve the problem. It's just the vague phrases of the requirements, so I'm really lost. Thanks for your time!!

Guadalupe Gagnon

Level 37 , Tampa, United States

20 August 2020, 22:47

I messaged you