CodeGym/Help with Java Tasks/What am I missing? I got stuck.

Level 41

Dąbrowa Górnicza

03.09.2020
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What am I missing? I got stuck.

Question about the task

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recommendation from your mentor A TestOrder object must be created in the createTestOrder method. Any help would be appreciated.

Currently, we have one tablet and 1 cook.
Let's create several tablets that will randomly generate orders, and we'll make two cooks.

1. In the Restaurant class, create a constant PRIVATE static int ORDER_CREATION_INTERVAL = 100.

2. In a separate file, create a (Runnable) RandomOrderGeneratorTask class. This task should:
2.1. Maintain a list of all the tablets
2.2. Use Math.random to select a random tablet.
2.3. RandomOrderGeneratorTask should have only one method.
2.4. Generate a random order every ORDER_CREATION_INTERVAL milliseconds for the tablet in item 2.2 (don't display a stack trace)
Now an order is created in the Tablet class's createOrder method.
In the Tablet class, create a void createTestOrder() method with similar functionality that will randomly generate an order with random dishes without communicating with a real person.
Pass all the necessary data to in the constructor.

Hint:
a) create a TestOrder class (descendant of Order) in the parent's package.
b) in the Order class, create a protected initDishes() method that initializes the dishes. Call this method in the constructor
c) in the Order class, make the dishes field protected
d) override initDishes in the TestOrder class. Initialize the order with a random set of dishes.
e) instead of creating an Order object in the Tablet class's createTestOrder() method, create a TestOrder object.
All of the createTestOrder method's other functionality remains the same

3. Refactor the createTestOrder() and createOrder() methods: in one of the methods, select the code that is repeated in both methods, press Ctrl+Alt+M, enter any name for the method, and click OK. IDEA will offer to replace the code in the second method. Confirm the action.

Requirements:

A constant private static int ORDER_CREATION_INTERVAL with the value 100 must be created in the Restaurant class.
The RandomOrderGeneratorTask must be implemented in accordance with the task conditions.
The TestOrder class must be implemented in accordance with the task conditions.
The Order class must have an initDishes method that initializes dishes.
The Order class constructor must call the initDishes method.

package com.codegym.task.task27.task2712; import com.codegym.task.task27.task2712.kitchen.Cook; import com.codegym.task.task27.task2712.kitchen.Waiter; public class Restaurant { private static final int ORDER_CREATION_INTERVAL = 100; public static void main(String[] args) throws InterruptedException { Tablet tablet = new Tablet(1); Cook amigoCook = new Cook("Amigo"); Waiter waiter = new Waiter(); amigoCook.addObserver(waiter); tablet.addObserver(amigoCook); tablet.createOrder(); Cook proffesorCook = new Cook("Proffesor"); RandomOrderGeneratorTask task1 = new RandomOrderGeneratorTask(ORDER_CREATION_INTERVAL, proffesorCook); task1.run(); ManagerTablet managerTablet = new ManagerTablet(); managerTablet.printAdRevenue(); managerTablet.printCookUtilization(); managerTablet.printActiveVideoSet(); managerTablet.printArchivedVideoSet(); } }

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Guadalupe Gagnon

Level 37 , Tampa, United States

3 September 2020, 18:17

Remove line 12 of the test order class. The super constructor calls initDishes() before that line is reached and this line is throwing out the already filled "dishes" ArrayList and replacing it with a blank ArrayList.

brus5

Level 41 , Dąbrowa Górnicza, Poland

3 September 2020, 19:15

Thanks Guadalupe for fast response. I've removed it and still the same error. When I don't initiate a new ArrayList<>(), I've got NullPointerException.

Exception in thread "main" java.lang.NullPointerException
	at com.codegym.task.task27.task2712.kitchen.TestOrder.initDishes(TestOrder.java:21)
	at com.codegym.task.task27.task2712.kitchen.Order.<init>(Order.java:15)
	at com.codegym.task.task27.task2712.kitchen.TestOrder.<init>(TestOrder.java:11)
	at com.codegym.task.task27.task2712.Tablet.createTestOrder(Tablet.java:39)
	at com.codegym.task.task27.task2712.RandomOrderGeneratorTask.run(RandomOrderGeneratorTask.java:37)
	at com.codegym.task.task27.task2712.Restaurant.main(Restaurant.java:19)

I moved initiation to initDishes() in TestOrder class but still the same error occurs.

Guadalupe Gagnon

Level 37 , Tampa, United States

3 September 2020, 19:28

The error is started on line 21 of the TestOrder class because the "dishes" arraylist is null when this method is called. All those lines are just the path the code took to get to that point starting with - main method line 19 then - RandomOrderGeneratorTask.run method line 37 then - Tablet.createTestOrder line 39 then - TestOrder.<init> (this is the constructor) line 11 then - Order.<init> (constructor) line 15 and finally - TestOrder.initDishes method line 21 In all that, each line is the call from one method leading to the next line call. Just to be sure, has line 12 been removed and does your method look like this?:

protected void initDishes() {
   dishes = new ArrayList<>();
   int randomSetOfDishes = getRandom(1, 6);

   for (int i = 0; i < randomSetOfDishes; i++) {
      int random = getRandom(0, 4);
      super.dishes.add(Dish.values()[random]);
   }
}

brus5

Level 41 , Dąbrowa Górnicza, Poland

3 September 2020, 19:34

Exactly.

protected void initDishes() {
    dishes = new ArrayList<>();
    int randomSetOfDishes = getRandom(1, 6);

    for (int i = 0; i < randomSetOfDishes; i++) {
        int random = getRandom(0, 4);
        dishes.add(Dish.values()[random]);
    }
}

Guadalupe Gagnon

Level 37 , Tampa, United States

3 September 2020, 19:50

Are there any other changes that were made from this code in the Order or TestOrder class? I pasted a bunch of your code in to test on my IntelliJ and it is working as intended.

Guadalupe Gagnon

Level 37 , Tampa, United States

3 September 2020, 19:54

useful

Actually, from the error code you posted above, it says a method call is on line 39 of the tablet class, but it should be line 43. how has that method changed since posting this original post?

brus5

Level 41 , Dąbrowa Górnicza, Poland

3 September 2020, 20:29

package com.codegym.task.task27.task2712;

import com.codegym.task.task27.task2712.ad.AdvertisementManager;
import com.codegym.task.task27.task2712.ad.NoVideoAvailableException;
import com.codegym.task.task27.task2712.kitchen.Order;
import com.codegym.task.task27.task2712.kitchen.TestOrder;

import java.io.IOException;
import java.util.Observable;
import java.util.logging.Level;
import java.util.logging.Logger;

public class Tablet extends Observable {
    private final int number;
    private static java.util.logging.Logger logger = Logger.getLogger(Tablet.class.getName());

    public Tablet(int number) {
        this.number = number;
    }

    public Order createOrder() {
        Order order = null;
        try {
            order = new Order(this);
            if (!order.isEmpty()) {
                processOrder(order);
            }
        } catch (IOException ex) {
            logger.log(Level.SEVERE, "The console is unavailable.");
        } catch (NoVideoAvailableException e) {
            logger.log(Level.INFO, "No video is available for the following order: " + order);
        }
        return order;
    }

    public TestOrder createTestOrder() {
        TestOrder order = null;
        try {
            order = new TestOrder(this);
            processOrder(order);
        } catch (IOException e) {}

        return order;
    }

    private void processOrder(Order order) {
        setChanged();
        notifyObservers(order);
        int seconds = order.getTotalCookingTime() * 60;
        AdvertisementManager manager = new AdvertisementManager(seconds);
        manager.processVideos();
    }

    @Override
    public String toString() {
        return "Tablet{" +
                "number=" + number +
                '}';
    }
}

I am desperately looking for solution :P

brus5

Level 41 , Dąbrowa Górnicza, Poland

3 September 2020, 20:32

package com.codegym.task.task27.task2712.kitchen;

import com.codegym.task.task27.task2712.Tablet;

import java.io.IOException;
import java.util.ArrayList;

public class TestOrder extends Order {

    public TestOrder(Tablet tablet) throws IOException {
        super(tablet);
    }

    @Override
    protected void initDishes() {
        dishes = new ArrayList<>();
        int randomSetOfDishes = getRandom(1, 6);

        for (int i = 0; i < randomSetOfDishes; i++) {
            int random = getRandom(0, 4);
            dishes.add(Dish.values()[random]);
        }
    }

    private int getRandom(int min, int max) {
        return (int) (Math.random() * (max - min + 1) + min);
    }
}

brus5

Level 41 , Dąbrowa Górnicza, Poland

3 September 2020, 20:44

solution

@Guadalupe I solved it in 47 attempts! :D Seriously sometimes I feel like completely retard. I guess I tested everything. The last thing I've changed was changing method type to void without return value and it worked! :)

public void createTestOrder() {
    TestOrder order;
    try {
        order = new TestOrder(this);
        processOrder(order);
    } catch (IOException e) {}
}

Guadalupe Gagnon

Level 37 , Tampa, United States

3 September 2020, 20:51

I didn't even pick that up LOL. I see now that the task conditions say to make that method void.... I should have caught that earlier. Glad you solved it!

Szymon

Level 41 , Warsaw, Poland

24 June 2021, 12:06

Oh god such a stupid thing. Thanks guys for finding the issue.