Visual basic LINQ錯誤

Question

任何人都知道爲什麼我有這個錯誤？

我收到以下錯誤：

Object reference not set to an instance of an object

這裏是LINQ問題。感謝您提前提供任何幫助。

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 

Answer 1

請問如果你改變了第一線，以它的工作：

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

這表明那裏的座位列表中的空值，並且高於Where拉姆達應該刪除它們。

Answer 2

你的Where子句對我來說很陌生。你不應該使用=運算符，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 

你確定每行都用空格而不是別的東西分隔嗎？即使在那裏也不應該導致一個空值。

這裏是我的示例程序，似乎工作（在LinqPad測試它似乎不支持隱式行繼續符）：

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