Visual basic LINQ错误

任何人都知道为什么我有这个错误？Visual basic LINQ错误

我收到以下错误：

Object reference not set to an instance of an object

这里是LINQ问题。感谢您提前提供任何帮助。

Dim q = From line In seats 
     Let data = line.Split(New [Char]() {" "c}, StringSplitOptions.RemoveEmptyEntries) ' it occurs in this line ' 
     Let seatA = data(0) 
     Let seatB = data(1) 
     Let seatC = data(2) 
     Let seatD = data(3) 
     Let seatE = data(4) 
     Let seatF = data(5) 
     Where seatA Is "." 
     Where seatB Is "." 
     Select seatA, seatF

来源

2012-04-15 amedeiros

你尝试，我在我的回答对您的最后一个问题的变化？ – 2012-04-15 15:09:06

这很可能意味着你在'seat'集合中有一些'null'条目。 – svick 2012-04-15 15:11:13

@MarkHall是的，我试过你的更正，它在LINQ上没有任何区别。我想我可能会有空条目，所以我可能会尝试另一个循环来删除它们，并将只有有效的条目放入一个新的数组。编辑：这没有奏效，我仍然得到空引用。 – amedeiros 2012-04-15 15:22:06

请问如果你改变了第一线，以它的工作：

Dim windowSeatQuery = From line In seats.Where(function (s) s isnot nothing)

这表明那里的座位列表中的空值，并且高于Where拉姆达应该删除它们。

来源

2012-04-15 16:04:36

你的Where子句对我来说很陌生。你不应该使用=运算符，而不是：

Dim q = From line In seats 
    Let data = line.Split(New [Char]() {" "c}, StringSplitOptions.RemoveEmptyEntries) ' it occurs in this line ' 
    Let seatA = data(0) 
    Let seatB = data(1) 
    Let seatC = data(2) 
    Let seatD = data(3) 
    Let seatE = data(4) 
    Let seatF = data(5) 
Where seatA = "." AndAlso seatB = "." '<------ Use = on this line not Is 
Select seatA, seatF

你确定每行都用空格而不是别的东西分隔吗？即使在那里也不应该导致一个空值。

这里是我的示例程序，似乎工作（在LinqPad测试它似乎不支持隐式行继续符）：

Sub Main 
    Dim seats As New List(Of String)() 
    seats.Add("1 2 3 4 5 6") 
    seats.Add(". . 9 8 7 6") 
    seats.Add(". . 5 5 5 5") 
    seats.Add("1 2 3 4 5 6") 
    seats.Add(". . 2 4 6 8") 
    seats.Add("1 2 3 4 5 6") 

    Dim q = From line In seats _ 
     Let data = line.Split(New [Char]() {" "c}, StringSplitOptions.RemoveEmptyEntries) _ 
     Let seatA = data(0) _ 
     Let seatB = data(1) _ 
     Let seatC = data(2) _ 
     Let seatD = data(3) _ 
     Let seatE = data(4) _ 
     Let seatF = data(5) _ 
    Where seatA = "." AndAlso seatB = "." _ 
    Select seatA, seatF 

    q.Dump() 
End Sub

来源

2012-04-16 17:42:23

Visual basic LINQ错误

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