Question

我的课程定义如下。没有太多细节我不希望任何人能够改变这个实例化对象，或者传递给这个类构造函数的对象。

public class ItemDeliveryInfo
{
    public ItemDeliveryAudit ItemDeliveryAudit
    {
        get
        {
            return this._itemDeliveryAudit;
        }
    }
    public int ItemDeliveryAuditId
    {
        get
        {
            return this.ItemDeliveryAudit.ItemDeliveryAuditId;
        }
    }
    public int? DeliveryDriverId
    {
        get
        {
            return this.ItemDeliveryAudit.DeliveryDriverId;
        }
    }
    public int DeliveryId
    {
        get
        {
            return this.ItemDeliveryAudit.DeliveryId;
        }
    }
    public int StoreId
    {
        get
        {
            return this.ItemDeliveryAudit.StoreId;
        }
    }

    private ItemDeliveryAudit _itemDeliveryAudit;
    private bool _isItemLate;
    private bool _isItemOnTime;

    internal ItemDeliveryInfo(ItemDeliveryAudit itemDeliveryAudit, bool itemLate, bool itemOnTime)
    {
        this._itemDeliveryAudit = drAssignedAudit;
        this._isItemLate = itemLate;
        this._isItemOnTime = itemOnTime;
    }
    public bool IsItemLate()
    {
        return this._isItemLate;
    }

    public bool IsItemOnTime()
    {
        return this._isItemOnTime;
    }
}

目前构造函数用于创建单个ItemDeliveryInfo对象并成功返回我想要的对象...

 ItemDeliveryInfo infoObject = new ItemDeliveryInfo(itemAudit, true, false);

但是，我无法理解如下所示的构造函数......

List<ItemDeliveryAudits> itemDeliveryAudits = // code to populate list to pass to the ctor;
List<ItemDeliveryInfo> itemDeliveryInfos = new ItemDeliveryInfo(itemDeliveryAudits, true, false);

我假设我必须创建另一个重载的构造函数来处理这个问题，但我对如何实现这一点感到茫然。任何帮助或指导将不胜感激。

Answer 1

只需使用LINQ和当前的ctor：

List<ItemDeliveryInfo> itemDeliveryInfos = 
          itemDeliveryAudits.Select(i => new ItemDeliveryInfo(i, true, false)).ToList();

Answer 2

如果您执行“new ItemDeliveryInfo”，您将始终获得“ItemDeliveryInfo”的单个实例。除了构造函数的类型之外，构造函数无法返回任何其他内容 - 它显然可以执行类似

的操作

List<ItemDeliveryInfo> itemDeliveryInfos = new ItemDeliveryInfo(itemDeliveryAudits, true, false);

您可以通过创建静态方法或工厂来完成您想要的任务，如下所示：

public static List<ItemDeliveryInfo> GetItemDeliveryInfo(List<ItemDeliveryAudits> audits) {
   var list = new List<ItemDeliveryinfo>();
   foreach (var deliveryAudit in audits)
   {
       list.Add(new ItemDeliveryInfo(deliveryAudit));
   }
}

Answer 3

您可以使用LINQ：

List<ItemDeliveryAudits> itemDeliveryAudits = // code to populate list to pass to the ctor;
List<ItemDeliveryInfo> itemDeliveryInfos = itemDeliveryAudits
    .Select(item => new ItemDeliveryInfo(item, true, false))
    .ToList();

C＃如何通过构造函数

3 个答案: