asp.net - 作为结构成员的列表与另一个结构相关联（列表具有另一个结构的对象作为参数）

Question

代码在 vb.net

Structure FeeComponent 
    Public id As Integer
    Public sName As String
    Public oFee As List(new FeeDetail) 
End Structure

另一种结构

Structure FeeDetail

    Public rollNo As Integer
    Public address As String
    Public age As Integer

End Structure

在函数中执行 sql 查询并将结果存储在 Reader 中，我想以以下方式向主结构费用组件添加一些详细信息

Dim Retval As New List(Of Idemo.FeeComponent)
Dim Fee As New List(Of Idemo.FeeDetail)

Dim Temp As New Idemo.FeeComponent
Dim Fees As New Idemo.FeeDetail

While Reader.Read

            With Temp
                .id = Reader.Item("id")
                .sName = Reader.Item("Name")
With Fees
                .rollNo = Reader.Item("roll")
    .address = Reader.Item("add")
    .age = Reader.Item("age")
            Temp.Fee.Add(Fees)
        End While

在 Temp.Fee.Add(Fees) 行显示错误如何更正代码我已尽我所能，但我无法更正代码。我刚开始使用 vb 所以请帮助错误消息是 System.NullReferenceException: object reference not set to an instance of an object

标签： asp.netvb.net