ShopInventory2.java

import java.util.Stack;
import java.util.Queue;
import java.util.LinkedList;
import java.util.Map;
import java.util.LinkedHashMap;
/**
 * Class Itemi
 * Represents Food Items
 * has name, weight, price
 */
class Item {
    private final String name;
    private final double price;

    /**
     * Creates an Item
     * @param name of item
     * @param price of item
     */
    Item(String name, double price) {
        this.name = name;
        this.price = price;
    }

    public String getName() {
        return this.name;
    }
    public double getPrice() {
        return this.price;
    }

    public String toString() {
        return this.name + " " + this.price;
    }
}

class Basket {
    private final Stack<Item> basket;

    Basket() {
        this.basket = new Stack<Item>();
    }

    public void addItem(Item item) {
        this.basket.push(item);
    }

    public Item removeItem() {
        if (this.basket.isEmpty()) {
            return null;
        }
        return this.basket.pop();
    }

    public boolean isEmpty() {
        return this.basket.isEmpty();
    }

    public String toString() {
        return "basket:" + this.basket.toString();
    }
}

class Checkout {
    private final Queue<Item> checkout;

    Checkout(Basket basket) {
        this.checkout = new LinkedList<Item>();
        while (!basket.isEmpty()) {
            Item item = basket.removeItem();
            addItem(item);
        }
    }

    public void addItem(Item item) {
        this.checkout.add(item);
    }

    public Item removeItem() {
        if (this.checkout.isEmpty()) {
            return null;
        }
        return this.checkout.remove();
    }

    public boolean isEmpty() {
        return this.checkout.isEmpty();
    }

    public String toString() {
        return "checkout:" + this.checkout.toString();
    }
}


class Bill {
    private final Map<String,Integer> basket;
    private double price;

    Bill(Checkout checkout) {
        // TODO - initialise Map, set price, bill items from checkout
        // first, create the Map for the basket - just like Queue,
        // you must select an implementation such as LinkedHashMap
        // second, our starting price is zero - there are no items yet
        // third, iterate through the checkout items -
        // take an item out of the checkout, and bill it

        this.basket = new LinkedHashMap<String,Integer>(); // Initialize the Map
        this.price = 0.0;
        while (!checkout.isEmpty()) {
            Item item = checkout.removeItem();
            billItem(item);
        }
    }

    public void billItem(Item item) {
        // TODO - put item in map, keep count of same items being billed
        // Note that the Map is from key String to value Integer
        // Items have names as Strings and count of items is an integer
        // first, check if the Item already exists in the Map -
        // the Item name is what we use as the key
        // If it exists - we need to increment its counter by 1
        // If not - we need to create a new key with the item name and value 1
        // second, add the item's price to the bill total price

        if (this.basket.containsKey(item.getName())) {
            this.basket.put(item.getName(), this.basket.get(item.getName()) + 1);
        } else {
            this.basket.put(item.getName(), 1);
        }
        this.price += item.getPrice();

    }

    public double getTotal() {
        return this.price;
    }

    public String toString() {
        String output = "";
        for(String item: this.basket.keySet()) {
            output += item + " (" + this.basket.get(item) + "nos)\n";
        }
        return output + "total: " + this.price;
    }
}


class ShopInventory2{
public static void main(String[] args) {
    Basket basket = new Basket();
    loadBasket(basket);
    // System.out.println(basket); // for DEBUG
    Checkout checkout = new Checkout(basket);
    // System.out.println(checkout); // for DEBUG
    Bill bill = new Bill(checkout);
    System.out.println(bill);
}

static void loadBasket(Basket basket) {
    basket.addItem(new Item("Twinings Earl Grey Tea", 4.50));
    basket.addItem(new Item("Folans Orange Marmalade", 4.00));
    basket.addItem(new Item("Free-range Eggs", 3.35));
    basket.addItem(new Item("Brennan's Bread", 2.15));
    basket.addItem(new Item("Ferrero Rocher", 7.00));
    basket.addItem(new Item("Ferrero Rocher", 7.00));
}
}