1迭代后的循环停止(For-Loop Stopping after 1 Iteration)

 对于我的这部分工作，我需要做以下事情： 
 
 
 
 创建一个函数，该函数返回字符串类型键和整数类型值的排序列表。 在函数内部，声明一个新的排序列表，其结构与函数的返回类型相同。 然后，使用嵌套for循环填充排序列表，浏览产品列表和年份列表，以便将产品和年份连接在一起以创建密钥，并从请求表数组中检索相应的需求值作为值将此键输入到排序列表中。 
 
 
 我编写了以下代码来执行此操作，但是在1次迭代后它会在System.dll中抛出“System.ArgumentException”。 测试MessageBox将仅显示“ModelX 2013 205”，然后将抛出错误。 
 
    Public Function GetProductDemand() As SortedList(Of String, Integer)
    Dim prodDemand As New SortedList(Of String, Integer)

    Dim count As Integer = 0
    For Each product In products
        For Each yr In years
            Dim key As String
            key = product & " " & yr
            For i As Integer = 0 To 4
                prodDemand.Add(key, demand(count, i)) 'stops here after 1 iteration
                MessageBox.Show(key & " " & prodDemand(key)) 'test to display results
            Next
        Next
        count += 1
    Next
    Return prodDemand
End Function
 
 出现这种情况的原因是什么？ 以下是相关代码的其余部分： 
 
    Dim products As List(Of String)
Dim years As List(Of String)
Dim demandList As SortedList(Of String, Integer)
Dim demand As Integer(,)

Private Sub frmDemand_Load(sender As Object, e As EventArgs) Handles MyBase.Load
    products = GetProducts()
    years = GetYears()
    demand = GetDemand()
    demandList = GetProductDemand()
End Sub

Private Function GetDemand() As Integer(,)
    Return {
            {205, 220, 245, 230},
            {160, 174, 152, 144},
            {480, 424, 396, 456}
           }
End Function

Public Function GetProducts() As List(Of String)
    Dim prods As New List(Of String)
    prods.Add("ModelX")
    prods.Add("ModelY")
    prods.Add("ModelZ")
    Return prods
End Function

Public Function GetYears() As List(Of String)
    Dim yr As New List(Of String)
    yr.Add("2013")
    yr.Add("2014")
    yr.Add("2015")
    yr.Add("2016")
    Return yr
End Function

For this part of my assignment I need to do the following:
 
 
 
Create a function that returns a sorted list of string type keys and integer type values. Inside the function, declare a new sorted list that has the same structure as the function’s return type. Then, using a nested for loop for populating the sorted list, go through the product list and year list such that the product and year is concatenated together to create a key, and the corresponding demand value from the demand table array is retrieved as the value for this key to be entered to the sorted list.
 
 
I've written the following code to do that, however it throws "'System.ArgumentException' in System.dll" after 1 iteration. The test MessageBox will only display "ModelX 2013 205" and then the error will be thrown.
 
    Public Function GetProductDemand() As SortedList(Of String, Integer)
    Dim prodDemand As New SortedList(Of String, Integer)

    Dim count As Integer = 0
    For Each product In products
        For Each yr In years
            Dim key As String
            key = product & " " & yr
            For i As Integer = 0 To 4
                prodDemand.Add(key, demand(count, i)) 'stops here after 1 iteration
                MessageBox.Show(key & " " & prodDemand(key)) 'test to display results
            Next
        Next
        count += 1
    Next
    Return prodDemand
End Function
 
Any reason why this is happening? Here's the rest of the relevant code:
 
    Dim products As List(Of String)
Dim years As List(Of String)
Dim demandList As SortedList(Of String, Integer)
Dim demand As Integer(,)

Private Sub frmDemand_Load(sender As Object, e As EventArgs) Handles MyBase.Load
    products = GetProducts()
    years = GetYears()
    demand = GetDemand()
    demandList = GetProductDemand()
End Sub

Private Function GetDemand() As Integer(,)
    Return {
            {205, 220, 245, 230},
            {160, 174, 152, 144},
            {480, 424, 396, 456}
           }
End Function

Public Function GetProducts() As List(Of String)
    Dim prods As New List(Of String)
    prods.Add("ModelX")
    prods.Add("ModelY")
    prods.Add("ModelZ")
    Return prods
End Function

Public Function GetYears() As List(Of String)
    Dim yr As New List(Of String)
    yr.Add("2013")
    yr.Add("2014")
    yr.Add("2015")
    yr.Add("2016")
    Return yr
End Function

原文：https://stackoverflow.com/questions/42426120