Restaurant

Address.java

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+public class Address {
+    private double latitude;
+    private double longitude;
+    private String written_address;
+
+    public Address(double latitude, double longitude, String written_address) {
+        this.latitude = latitude;
+        this.longitude = longitude;
+        this.written_address = written_address;
+    }
+
+    public double getLatitude() {
+        return latitude;
+    }
+
+    public double getLongitude() {
+        return longitude;
+    }
+
+    public String getWrittenAddress() {
+        return written_address;
+    }
+
+    public double distanceFrom(Address otherAddress) {
+        double lat1 = (this.latitude);
+        double lon1 = (this.longitude);
+        double lat2 = (otherAddress.getLatitude());
+        double lon2 = (otherAddress.getLongitude());
+
+        double dLat = lat2 - lat1;
+        double dLon = lon2 - lon1;
+
+        double distance = Math.sqrt(Math.pow(dLat, 2) + Math.pow(dLon, 2));
+
+
+
+        return distance;
+    }
+}

Customer.java

@@ -0,0 +1,32 @@
+public class Customer {
+    private static int nextCustomerNumber = 1;
+    private int customerNumber;
+    private String name;
+    private Address address;
+
+    public Customer(String name, Address address) {
+        this.customerNumber = nextCustomerNumber++;
+        this.name = name;
+        this.address = address;
+    }
+
+    public int getCustomerNumber() {
+        return customerNumber;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public Address getAddress() {
+        return address;
+    }
+
+    public void setAddress(Address address) {
+        this.address = address;
+    }
+}

Food.java

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+import java.util.Vector;
+
+public class Food {
+    private static Vector<Food> menu = new Vector<>();
+    private String name;
+    public int price;
+
+    public Food(String name, int price) {
+        this.name = name;
+        this.price = price;
+        menu.add(this);
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public int getPrice() {
+        return price;
+    }
+
+    public static Vector<Food> getMenu() {
+        return menu;
+    }
+}

Invoice.java

@@ -0,0 +1,57 @@
+import java.util.Vector;
+
+class Invoice {
+    private static final float tax_rate = 9.4f;
+    private int state;
+    private Customer customer;
+    private Vector<Item> items;
+
+    public Invoice(Customer customer) {
+        this.state = -1;
+        this.customer = customer;
+        this.items = new Vector<>();
+    }
+
+    public int getState() {
+        return state;
+    }
+
+    public Customer getCustomer() {
+        return customer;
+    }
+
+    public boolean addItem(Item item) {
+        if (state != -1)
+            return false;
+
+        items.add(item);
+        return true;
+    }
+
+    public boolean removeItem(Item item) {
+        if (state != -1)
+            return false;
+
+        return items.remove(item);
+    }
+
+    public void nextStage() {
+        state++;
+    }
+
+    public Vector<Item> getItems() {
+        return items;
+    }
+
+    public int getTotalPrice() {
+        int totalPrice = 0;
+        for (Item item : items) {
+            totalPrice += item.getFood().getPrice() * item.getCount();
+        }
+
+        float taxAmount = (totalPrice * tax_rate) / 100;
+
+        int totalPriceWithTax = Math.round(totalPrice + taxAmount);
+        return totalPriceWithTax;
+    }
+}

Item.java

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+class Item {
+    private Food food;
+    private int count;
+    private String description;
+
+    public Item(Food food, int count, String description) {
+        this.food = food;
+        this.count = count;
+        if (description == null) {
+            this.description = "-";
+        } else {
+            this.description = description;
+        }
+    }
+
+    public Food getFood() {
+        return food;
+    }
+
+    public int getCount() {
+        return count;
+    }
+
+    public String getDescription() {
+        return description;
+    }
+
+
+}

Restaurant.java

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+public class Restaurant{
+    public static void main(String[] args) {
+        Address a1 = new Address(2, 3, "Lahijan");
+        Address a2 = new Address(5, 6, "Tehran");
+
+        System.out.println("\n--------------------------------------\n");
+        System.out.println("Distance From Address a1 to a2 is: " + a1.distanceFrom(a2));
+        System.out.println("\n--------------------------------------\n");
+
+        Customer c1 = new Customer("MAMAD", a1);
+        Customer c2 = new Customer("ALI", a2);
+
+        System.out.println("First Customer's ID: " + c1.getCustomerNumber());
+        System.out.println("Second Customer's ID: " + c2.getCustomerNumber());
+
+        Food f1 = new Food("BURGER", 130);
+        Food f2 = new Food("PIZZA", 200);
+        Food f3 = new Food("PASTA", 110);
+
+        System.out.println("\n--------------------------------------\n");
+
+        for (int i = 0; i < Food.getMenu().size(); i++) {
+            System.out.println("Food Name: " + Food.getMenu().get(i).getName());
+        }
+
+        System.out.println("\n--------------------------------------\n");
+
+        Item it1 = new Item(f1, 2,null);
+        Item it2 = new Item(f2, 3, "MORE SAUCE");
+        Item it3 = new Item(f3, 1, null);
+
+        Invoice inv = new Invoice(c1);
+
+        if (inv.addItem(it1) && inv.addItem(it2)) System.out.println("Items added successfully");
+        else System.out.println("Items could not be added");
+
+        if (inv.removeItem(it3)) System.out.println("Item removed successfully");
+        else System.out.println("Failed to remove item (item doesn't exist in invoice)");
+
+        inv.nextStage();
+
+        System.out.println("Current state: " + inv.getState());
+
+        System.out.println("\n--------------------------------------\n");
+
+        for (int i = 0; i < inv.getItems().size(); i++) {
+            Item it = inv.getItems().get(i);
+            System.out.println("Food Name: " + it.getFood().getName() + " | Food Description: " + it.getDescription());
+        }
+
+        System.out.println("Total price: " + inv.getTotalPrice());
+    }
+}