public class RestaurantService {
    private ArrayList<Product> allProducts =  new ArrayList<Product>();
    private ArrayList<Order> allOrders = new ArrayList<Order>();

    private OrderDAO oDao = new OrderDAO();
    private ProductDAO pDao = new ProductDAO();
    private OrderProductDAO opDao = new OrderProductDAO();



    public void addProduct(int id, String nm, int sk, double pr){
        if(allProducts.contains(nm)){
            throw new IllegalArgumentException("Product Bestaat al!");

        }
        else{
            Product p = new Product(id, sk, nm, pr);
            allProducts.add(p);
        }
    }

    public void addOrderForTable(int productID, int amount, Order o){
        OrderProduct oP = new OrderProduct(productID, amount);
        o.addProduct(oP);
    }

    public List<Product> showAllProducts() throws ClassNotFoundException{
        return pDao.findAll();
    }

    public Product findProductbyID(int productID) throws ClassNotFoundException{
        Product p = pDao.findByID(productID);
        return p;
    }

    public List<OrderProduct> showAllOrderedProducts(int tableNR, Order o) throws ClassNotFoundException {
        return opDao.findOrderByTableNR(tableNR);
    }

    public List<Order> showAllTables() throws ClassNotFoundException {
        return oDao.findAllTables();
    }

    public void deleteProduct(int productID) throws ClassNotFoundException {
        Product p = pDao.findByID(productID);

        if (p != null) {
            pDao.delete(p);
        } else throw new IllegalArgumentException("Id does not exist!");
    }
}

import java.util.ArrayList;


public class Order {
    private int orderID;
    private int tableNR;
    private ArrayList<OrderProduct> deBesteldeProducten;

    public Order(int orderID, int tableNR){
        this.orderID = orderID;
        this.tableNR = tableNR;
    }

    public int getOrderID(){
        return orderID;
    }
    public int getTableNR(){
        return tableNR;
    }

    public void addProduct(OrderProduct oP){
        deBesteldeProducten.add(oP);
    }

    public ArrayList<OrderProduct> getOrderProduct(){
        return deBesteldeProducten;

    }

    public double orderBedrag(){
        double total = 0;
        for(OrderProduct oP : deBesteldeProducten){
            total += oP.productPrice();
        }
        return total;
    }

}

package ordermap.model;

import java.util.Collections;
import java.util.List;


public class OrderProduct {
    private int amount;
    private Order order;
    private Product hetProduct;

    public OrderProduct(Order order, int amount){
        this.amount = amount;
        this.order = order;
        this.hetProduct = getHetProduct();

    }

    public int getAmount(){
        return amount;
    }

    public Order getOrder(){
        return order;
    }

    public void setOrder(Order order){
        this.order = order;
    }

    public Product getHetProduct(){
        return hetProduct;
    }
    public void setProduct(Product hetProduct){
        this.hetProduct = hetProduct;
    }

    public double productPrice(){
        double total = 0;
        total = hetProduct.getPrice() * amount;
        return total;
    }
}

package ordermap.model;

public class Product {
    private int productID;
    private int stock;
    private String name;
    private double price;


    public Product(int id, int sk, String nm, double pr){
        productID = id;
        stock = sk;
        name = nm;
        price = pr;
    }

    public int getProductID(){
        return productID;
    }

    public int getStock(){
        return stock;
    }

    public String getName(){
        return name;
    }

    public double getPrice(){
        return price;
    }
}