封装和接口(Encapsulation and Interfaces)

 几天后，我一直在微软网站上的.NET教程中研究和学习这一特定课程。 链接 
 
 正如您可能已经知道，每节课结束时都会有“作业”。 这次我应该使用一些新功能升级给定项目并实现Encapsulation和Interfaces。 
 
 新功能应包括： 
 
 
 
 客户拥有揭露其历史订单的房产 
 //更新：已实施 
 
 
 客户公开了添加订单的方法 
 
 
 尝试添加空订单应该什么都不做 
 
 
 尝试使用现有OrderNumber添加订单应替换现有订单（不添加重复） 
 //我唯一成功的就是删除之前使用相同名称的“订单”，而不是仅仅替换它。 
 
 
 订单应该公开OrderDate（可以读/写） 
 
 
 尝试在将来添加订单和OrderDate应该什么都不做 
 
 
 我确实设法添加了大部分功能。 我的项目目前（ 更新 ）： 
 
namespace ConsoleApp2
{
class Program
{
    static void Main()
    {
        Customer customer1 = new Customer("John");
        Customer customer2 = new Customer("George");
        var customers = new List<Customer>() { customer1, customer2 };
        customer1.AddOrder("car", "12/7/1999"); // will be removed due to same name
        customer1.AddOrder("vase", "20/6/2024");// will not be added to the list because of the future time
        customer1.AddOrder("car", "3/12/2014");
        customer1.AddOrder("headphones", "3/12/2022");// will not be added to the list because of the future time
        customer2.AddOrder("headphones", "10/3/2002");
        customer2.AddOrder("", "");// will not be added to the list due to empty values

        //print customers

        foreach (var customer in customers)
        {
            customer.Print();
        }
    }
}
public class Customer
{
    public string Name { get; }
    private List<Order> orders = new List<Order>();
    private List<Order> ordersHistory = new List<Order>();


    public Customer(string name)
    {
        Name = name;
    }

    public void AddOrder(string name, string date)
    {
        if (name == null) { return; }
        else if (name == "" || date == "") { return; }
        else
        {
            AddHistoricOrder(name, date);
            AddRegularOrder(name, date);
        }


    }
    public void Print()
    {
        Console.WriteLine(Name);
        Console.Write("Orders: ");
        orders.ForEach(Console.Write);
        Console.WriteLine();
        Console.Write("Historic Orders: ");
        ordersHistory.ForEach(Console.Write);
        Console.WriteLine();
        Console.WriteLine($"Order Count: {orders.Count}");
        Console.WriteLine();
        Console.WriteLine();
    }

    private void AddRegularOrder(string name, string date)
    {

        if (DateTime.Parse(date) > DateTime.Now) { return; }
        else
        {

            for (int i = 0; i < orders.Count; i++)
            {
                if (orders[i].OrderName == name)
                {
                    orders.RemoveAt(i);
                }
            }
            orders.Add(new Order(name, date));

        }
    }
    private void AddHistoricOrder(string name, string date)
    {
        ordersHistory.Add(new Order(name, date));
    }
    public override string ToString()
    {
        return $"{Name}";
    }

}
public class Order
{
    public string OrderName { get; }
    public DateTime OrderDate { get; set; }

    public Order(string orderName, string date)
    {
        OrderName = orderName;
        OrderDate = DateTime.Parse(date);;
    }
    public override string ToString()
    {
        return $"{OrderName} ({OrderDate.ToShortDateString()}), ";
    }
}
}
 
 即使我搜索和观看各种视频的封装和接口，我仍然不确定我应该如何在这里实现它们。 你能帮我提高代码效率吗？ 
 
 我没有实现暴露历史订单的属性（我只是不确定应该做什么） 
 
 另外，我并没有真正理解“New is Glue”这一课程的一部分，它说我们应该避免在我们的代码中添加新的关键字，并展示一些使用接口的例子。 我没有找到给定LINK之外的任何信息我想如何避免在这个特定项目中创建新实例？ 提前致谢！ 

For a few days now I've been researching and studying about this particular lesson at .NET tutorials located at the Microsoft site. LINK
 
As you already may know there is a "homework" at the end of each lesson. This time I should upgrade the given project with some of the new features and implement Encapsulation and Interfaces.
 
New features should include:
 
 
 
Customers have a property exposing their historic Orders 
 
// update: implemented
 
 
Customers expose a method for adding an Order
 
 
Trying to add a null Order should do nothing 
 
 
Trying to add an Order with an existing OrderNumber should replace the existing Order (not add a duplicate) 
 
// the only thing I succeeded is removing the previous "orders" with the same name instead of just replacing it.
 
 
Orders should expose an OrderDate (which can be read/write)
 
 
Trying to add an order with an OrderDate in the future should do nothing
 
 
I did manage to add most of these features. My project currently(updated):
 
namespace ConsoleApp2
{
class Program
{
    static void Main()
    {
        Customer customer1 = new Customer("John");
        Customer customer2 = new Customer("George");
        var customers = new List<Customer>() { customer1, customer2 };
        customer1.AddOrder("car", "12/7/1999"); // will be removed due to same name
        customer1.AddOrder("vase", "20/6/2024");// will not be added to the list because of the future time
        customer1.AddOrder("car", "3/12/2014");
        customer1.AddOrder("headphones", "3/12/2022");// will not be added to the list because of the future time
        customer2.AddOrder("headphones", "10/3/2002");
        customer2.AddOrder("", "");// will not be added to the list due to empty values

        //print customers

        foreach (var customer in customers)
        {
            customer.Print();
        }
    }
}
public class Customer
{
    public string Name { get; }
    private List<Order> orders = new List<Order>();
    private List<Order> ordersHistory = new List<Order>();


    public Customer(string name)
    {
        Name = name;
    }

    public void AddOrder(string name, string date)
    {
        if (name == null) { return; }
        else if (name == "" || date == "") { return; }
        else
        {
            AddHistoricOrder(name, date);
            AddRegularOrder(name, date);
        }


    }
    public void Print()
    {
        Console.WriteLine(Name);
        Console.Write("Orders: ");
        orders.ForEach(Console.Write);
        Console.WriteLine();
        Console.Write("Historic Orders: ");
        ordersHistory.ForEach(Console.Write);
        Console.WriteLine();
        Console.WriteLine($"Order Count: {orders.Count}");
        Console.WriteLine();
        Console.WriteLine();
    }

    private void AddRegularOrder(string name, string date)
    {

        if (DateTime.Parse(date) > DateTime.Now) { return; }
        else
        {

            for (int i = 0; i < orders.Count; i++)
            {
                if (orders[i].OrderName == name)
                {
                    orders.RemoveAt(i);
                }
            }
            orders.Add(new Order(name, date));

        }
    }
    private void AddHistoricOrder(string name, string date)
    {
        ordersHistory.Add(new Order(name, date));
    }
    public override string ToString()
    {
        return $"{Name}";
    }

}
public class Order
{
    public string OrderName { get; }
    public DateTime OrderDate { get; set; }

    public Order(string orderName, string date)
    {
        OrderName = orderName;
        OrderDate = DateTime.Parse(date);;
    }
    public override string ToString()
    {
        return $"{OrderName} ({OrderDate.ToShortDateString()}), ";
    }
}
}
 
Even tho I searched and watched various videos for encapsulation and interfaces I'm still not sure how should I implement those in here. Could you help me making my code more efficient ?
 
I did not implement a property for exposing historic Orders (I'm just not sure what that is supposed to do)
 
Also I did not really understand one part of the lesson called "New is Glue" which says we should avoid adding new keyword to our code and showed some example using interfaces. I failed to find any info outside of the given LINK How am I suppose to avoid creating new instances in this particular project? Thanks in advance!

原文：https://stackoverflow.com/questions/44505752