Vb.net 在vb中添加到我的arraylist而不覆盖它

我只是问了一个问题，并相应地修改了代码。我写网页的方式有点不对劲。我的目标是只在第一次初始化数组，然后继续递增它。你能帮忙吗？ 这是我使用的代码：

Imports AjaxControlToolkit
Imports System.Data.SqlClient
Imports System.Configuration



Partial Class Shtick

    Inherits System.Web.UI.Page
    Dim conn As SqlConnection
    Dim comm As SqlCommand
    Dim reader As SqlDataReader
    Dim purimConnection As String = ConfigurationManager.ConnectionStrings("Purim").ConnectionString
    Dim ItemSelect As New ArrayList()



    Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load




        If ItemSelect.Count >  0 Then
            ItemSelect = New ArrayList()
            Session("itemInCart") = ItemSelect
        End If

        If Not IsPostBack Then
            FillShtickList()

        End If

    End Sub

    Protected Sub FillShtickList()

        Dim conn As SqlConnection
        Dim comm As SqlCommand
        Dim reader As SqlDataReader
        Dim purimConnection As String = ConfigurationManager.ConnectionStrings("Purim").ConnectionString
        conn = New SqlConnection(purimConnection)
        comm = New SqlCommand("SELECT RTRIM(ProductPrice) AS Price, ProductName, ProductImage, ProductID, ProductDescription FROM Products", conn)

        Try
            conn.Open()
            reader = comm.ExecuteReader()
            ShtickDataList.DataSource = reader
            ShtickDataList.DataBind()
            reader.Close()

        Finally
            conn.Close()

        End Try
    End Sub


    'Protected Sub ShtickDataList_ItemCreated(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.ListViewItemEventArgs) Handles ShtickDataList.ItemCreated
    '    'If e.Item.ItemType = ListItemType.Item Then
    '    '    Dim pce As ModalPopupExtender = e.Item.FindControl("PopupControlExtender1")
    '    '    Dim behaviorID As String
    '    '    behaviorID = "pce_" & e.Item.DataItemIndex
    '    '    pce.BehaviorID = behaviorID
    '    '    Dim img As Image = e.Item.FindControl("PI")

    'item select = which item was selected

    Dim Quantities As New ArrayList()
    Dim itemQtyOrdered As Integer



    Public Sub ShtickDataList_ItemCommand(ByVal source As Object, ByVal e As System.Web.UI.WebControls.ListViewCommandEventArgs) Handles ShtickDataList.ItemCommand

        If e.CommandName = "ViewCart" Then
            Response.Redirect("~/ShoppingCart.aspx")
        End If


        If e.CommandName = "addToCart" Then
            Dim itemQuantity As DropDownList = e.Item.FindControl("QuantityDropDown")
            itemQtyOrdered = itemQuantity.SelectedValue
            ItemSelect.Add(e.CommandArgument)
            Quantities.Add(itemQtyOrdered)

            Session("itemInCart") = ItemSelect
            Session("quantities") = Quantities


            viewInvoice()

        End If


    End Sub

    Protected Sub viewInvoice()

        Dim itemSelected As ArrayList = DirectCast(Session("itemInCart"), ArrayList)
        Dim QuantityofItem As ArrayList = DirectCast(Session("quantities"), ArrayList)

        Dim conn As SqlConnection
        Dim comm As SqlCommand
        Dim reader As SqlDataReader
        Dim purimConnection2 As String = ConfigurationManager.ConnectionStrings("Purim").ConnectionString
        conn = New SqlConnection(purimConnection2)

        comm = New SqlCommand("SELECT ProductName FROM Products WHERE ProductID = @ProductID", conn)

        'Dim i As Integer
        'For i = 0 To ItemSelect.Count - 1
        comm.Parameters.Add("@ProductID", Data.SqlDbType.Int)
        comm.Parameters("@ProductID").Value = (ItemSelected.Count - 1)

        'Next

        Try
            conn.Open()
            reader = comm.ExecuteReader()
            ViewCartlink.Text = "View Cart: (" & ItemSelected.Count & ")"



        Finally
            conn.Close()
        End Try
    End Sub

End Class


 End Try
    End Sub

End Class


 = CType(Session("itemInCart"), ArrayList)
            'al.Add(SS)
            'Session.Add("itemInCart", al)

            viewInvoice()

        End If


    End Sub

    Protected Sub viewInvoice()

        'Dim itemSelected As ArrayList = DirectCast(Session("itemInCart"), ArrayList)
        'Dim QuantityofItem As ArrayList = DirectCast(Session("quantities"), ArrayList)

        Dim conn As SqlConnection
        Dim comm As SqlCommand
        Dim reader As SqlDataReader
        Dim purimConnection2 As String = ConfigurationManager.ConnectionStrings("Purim").ConnectionString
        conn = New SqlConnection(purimConnection2)

        comm = New SqlCommand("SELECT ProductName FROM Products WHERE ProductID = @ProductID", conn)

        Dim i As Integer
        For i = 0 To ItemSelect.Count - 1
            comm.Parameters.Add("@ProductID", Data.SqlDbType.Int)
            comm.Parameters("@ProductID").Value = ItemSelect(i)

        Next

        Try
            conn.Open()
            reader = comm.ExecuteReader()
            ViewCartlink.Text = "View Cart: (" & ItemSelect.Count & ")"



        Finally
            conn.Close()
        End Try
    End Sub

End Class


M(ProductPrice) AS Price, ProductID, ProductName FROM Products WHERE ProductID = @ProductID", conn)
        comm = New SqlCommand("Insert into orders (UserID, ProductID, quantity) values (1, @ProductID, @Quantity)", conn)
        comm.Parameters.Add("@ProductID", Data.SqlDbType.Int)
        comm.Parameters("@ProductID").Value = item
        comm.Parameters.Add("@Quantity", Data.SqlDbType.Int)
        comm.Parameters("@Quantity").Value = qty

        'Dim i As Integer
        'For i = 0 To ItemSelect.Length - 1                                           
        '    comm.Parameters.Add("@ProductID", Data.SqlDbType.Int)
        '    comm.Parameters("@ProductID").Value = ItemSelect(i)
        'Next
        Try
            conn.Open()
            comm.ExecuteNonQuery()
            'reader = comm.ExecuteReader()
            'ShoppingList.DataSource = reader
            'ShoppingList.DataBind()
            'reader.Close()
        Finally
            conn.Close()
        End Try
    End Sub

在守则中：

If ItemSelect.Count >  0 Then
    ItemSelect = New ArrayList()
    Session("itemInCart") = ItemSelect
End If

你有一个比你应该有一个比。arraylist仅在数组中有项时初始化。因此，您只能在初始化数组后对其进行初始化。您需要的是：

If ItemSelect.Count >  0 Then
    ItemSelect = New ArrayList()
    Session("itemInCart") = ItemSelect
End If

---

请提出一个更具体的问题，并给出一个更简洁的例子。这是我的确切代码。我试图在我第一次单击按钮时使itemSelect数组初始化，它应该每次递增。在所有代码都需要递增一个变量之后？即使它与您的问题有关，它的后半部分也会出错，所以它是不可读的。你增加一个

ArrayList

的确切意思是什么？我理解什么是递增整数，但递增列表是没有意义的——至少在没有进一步解释的情况下是没有意义的。