添加到列表的新项目将覆盖上一个项目

问题描述

我在C#中使用List<>.我想在List中添加值.但是问题在于，第一项添加成功，但是当第二项将相同的值ovverride插入到第一个项中时，示例第一项abc成功插入，但是当第二项xyz到来时，它是ovveride abc到xyz以及两个项显示xyz.这是我的代码.

I am using List<> in C# . I want to add values in the List . But problem is that first item add successfully but when second item insert the same value ovverride into the first one , example first item abc inserted succefully but when second item xyz came it ovveride abc to xyz and both items shows xyz.Here is my code.

DataTable dtbl3 = new DataTable();
List<CartItems> lst = (List<CartItems>)Session["mycart"];
dtbl3 = DAL.Get("Select * from mytable");
List<EmailClass>  lstCstmer = new List<EmailClass>();
for (int j = 0; j < lst.Count; j++)
{
    emailLst.__EmailcstName = dtbl3.Rows[0]["cstm_name"].ToString();
    emailLst.__EmailcstLName = dtbl3.Rows[0]["cstm_LName"].ToString();
    emailLst.__EmailcstAddress = dtbl3.Rows[0]["cstm_Addr"].ToString();
    emailLst.__EmailcstPhoneNo = dtbl3.Rows[0]["cstm_Phone"].ToString();
    emailLst.__EmailcstCellNo = dtbl3.Rows[0]["cstm_CellNo"].ToString();
    emailLst.__EmailcstskypId = dtbl3.Rows[0]["cstm_skypeId"].ToString();
    emailLst.__EmailcstEmail = dtbl3.Rows[0]["cstm_email"].ToString();
    emailLst.__EmailcstCountry = dtbl3.Rows[0]["cstm_country"].ToString();
    emailLst.__EmailcstCity = dtbl3.Rows[0]["cstm_City"].ToString();
    emailLst.__EmailcstZipcode =Convert.ToInt32( dtbl3.Rows[0]["cstm_ZipCode"].ToString());
    emailLst.__EmailcstRemarks = dtbl3.Rows[0]["cstm_remarks"].ToString();
    emailLst._EmailCartProdName = lst[j]._CartProdName;
    emailLst._EmailCartProdPrice = lst[j]._CartProdPrice;
    emailLst._EmailCartProdQnty = lst[j]._CartProdQnty;
    emailLst._EmailCartProdCode = lst[j]._CartProdName;
    emailLst._EmailTotalProdPrice = lst[j]._TotalProdPrice;
    lstCstmer.Add(emailLst);
}

推荐答案

您要一遍又一遍地添加相同的项目，并且由于它是引用类型，因此列表中的所有条目都指向同一EmailClass实例.

You're adding the same item over and over again, and because it's a reference type all entries in the list point to the same instance of EmailClass.

在每次循环迭代中创建一个新实例来解决该问题:

Create a new instance in every loop iteration to fix that:

for (int j = 0; j < lst.Count; j++)
{
    emailLst = new EmailClass();

    emailLst.__EmailcstName = dtbl3.Rows[0]["cstm_name"].ToString();
    emailLst.__EmailcstLName = dtbl3.Rows[0]["cstm_LName"].ToString();
    emailLst.__EmailcstAddress = dtbl3.Rows[0]["cstm_Addr"].ToString();
    emailLst.__EmailcstPhoneNo = dtbl3.Rows[0]["cstm_Phone"].ToString();
    emailLst.__EmailcstCellNo = dtbl3.Rows[0]["cstm_CellNo"].ToString();
    emailLst.__EmailcstskypId = dtbl3.Rows[0]["cstm_skypeId"].ToString();
    emailLst.__EmailcstEmail = dtbl3.Rows[0]["cstm_email"].ToString();
    emailLst.__EmailcstCountry = dtbl3.Rows[0]["cstm_country"].ToString();
    emailLst.__EmailcstCity = dtbl3.Rows[0]["cstm_City"].ToString();
    emailLst.__EmailcstZipcode =Convert.ToInt32( dtbl3.Rows[0]["cstm_ZipCode"].ToString());
    emailLst.__EmailcstRemarks = dtbl3.Rows[0]["cstm_remarks"].ToString();

    emailLst._EmailCartProdName = lst[j]._CartProdName;
    emailLst._EmailCartProdPrice = lst[j]._CartProdPrice;
    emailLst._EmailCartProdQnty = lst[j]._CartProdQnty;
    emailLst._EmailCartProdCode = lst[j]._CartProdName;
    emailLst._EmailTotalProdPrice = lst[j]._TotalProdPrice;

    lstCstmer.Add(emailLst);

}

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