Arrays VB.NET |面板中的pictureboxes数组：对象引用未设置为对象的实例

在下面的代码中，我试图更改在数组“pictureboxes（9，9）”中创建的现有控件的标记。尝试执行此操作时，会出现错误“对象引用未设置为对象的实例”。这是在代码底部附近的checkdata子项中完成的，注释为“对象引用未设置为对象的实例。”

传递给sub的字符串是一个长的数字字符串，如果有帮助的话，PictureBoxe将被放置到layoutpanel中

我理解这个错误的意思，我知道pictureboxes（I，j）在被中断时等于零；我只是不知道怎么修理它

非常感谢您的帮助，希望我能尽快回答您的任何意见/答案

多谢各位

Imports System.Net.Sockets
Imports System.Threading
Imports System.Text
Imports System.Net

Public Class Form1
'0 as default tile, 1 as clicked, 3 as set mine (host perspective)
Dim tiles() As Integer = {0}
Public pictureboxes(9, 9) As PictureBox
Dim flagged() As Integer
Dim clicked As Integer()
Dim columns As Integer = 10
Dim rows As Integer = 10
Dim placedMinesCount As Integer = 0
Dim formattedTag As String()
Public turn As Boolean = False
Dim stringToSend As String

Public Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
    For i As Byte = 0 To 9
        For j As Byte = 0 To 9

            pictureboxes(i, j) = New PictureBox
            pictureboxes(i, j).Height = 60
            pictureboxes(i, j).Width = 60
            pictureboxes(i, j).ImageLocation = "0.png"
            pictureboxes(i, j).Tag = "0|" & i & ", " & j

            AddHandler pictureboxes(i, j).Click, AddressOf Tile_Click

            Dim column As Integer = j
            Dim row As Integer = i

            Panel.Controls.Add(pictureboxes(i, j), column, row)

        Next
    Next

    If Login.isHost = True Then
        Me.Text = "Set your mines (10)"
        turn = True
    ElseIf Login.isHost = False Then
        Me.Text = "Await your turn"
        btnEndTurn.Visible = False
        btnEndTurn.Enabled = False
    End If
End Sub

Protected Sub Tile_Click(ByVal sender As Object, ByVal e As EventArgs)
    formatSenderTag(sender.tag)
    If Login.isHost = True Then
        Dim clickAction As String = formattedTag(0)

        Select Case clickAction
            Case "0"
                If placedMinesCount < 10 Then
                    placedMinesCount = placedMinesCount + 1
                    sender.imagelocation = "3.png"
                    sender.tag = "3"
                    Me.Text = "Set your mines (" & 10 - placedMinesCount & ")"

                ElseIf placedMinesCount >= 10 Then
                    MsgBox("You have placed all of your 10 Mines")
                End If
            Case "2"
                MsgBox("You cannot set a mine here")
            Case "3"
                placedMinesCount = placedMinesCount - 1
                Me.Text = "Set your mines (" & 10 - placedMinesCount & ")"
                sender.imagelocation = "0.png"
                sender.tag = "0"
        End Select


    ElseIf Login.isHost = False Then
        Dim clickAction As String = formattedTag(0)
        Select Case clickAction
            Case "0"
                sender.tag = "1"
                sender.imagelocation = "1.png"
            Case "3"
                MsgBox("Game Over")
            Case "2"
                MsgBox("Already Clicked")
        End Select
    End If
End Sub

Private Sub formatSenderTag(ByVal sender As String)
    'split into array 
    'element 0 as TILE TYPE
    'element 1 as TILE LOCATION
    formattedTag = sender.Split(New String() {"|"}, StringSplitOptions.None)
End Sub

Private Sub Form_FormClosing(ByVal sender As Object, ByVal e As System.Windows.Forms.FormClosingEventArgs) Handles Me.FormClosing
    End
End Sub

Private Sub btnEndTurn_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnEndTurn.Click
    turn = False

    gridtostring()
    senddata()
End Sub

Private Sub gridtostring()
    For i As Byte = 0 To 9
        For j As Byte = 0 To 9
            formatSenderTag(pictureboxes(i, j).Tag & "|")
            stringToSend = stringToSend & formattedTag(0)
        Next
    Next
End Sub

Private Sub senddata()
    '***SEND STUFF
    'Assuming you have a textbox with the data you want to send
    If (Not String.IsNullOrEmpty(stringToSend)) Then
        Dim data() As Byte = Encoding.ASCII.GetBytes(stringToSend)
        Login.sendingClient.Send(data, data.Length)
    End If
End Sub

Public Sub checkdata(ByVal data As String)
    If Not data = stringToSend Then
        'Dim loopcount As Integer = 0
        For i As Byte = 0 To 9
            For j As Byte = 0 To 9
                Dim loopcount As Integer = (i.ToString & j.ToString) + 1
                'Dim pineapple As String = pictureboxes(i, j).Tag
                'pictureboxes(i, j).Tag = GetChar(data, 3)

                pictureboxes(i, j).Tag = GetChar(data, loopcount) & "|" & i & ", " & j '***Object reference not set to an instance of an object.***
                formatSenderTag(pictureboxes(i, j).Tag)
                pictureboxes(i, j).ImageLocation = formattedTag(0)
                pictureboxes(i, j).ImageLocation = "0.png"
                'Panel.Controls(pictureboxes(i, j).Tag) = GetChar(data, 3) '.Tag = GetChar(data, 3)

            Next
        Next
    End If
End Sub
End Class

***堆栈跟踪

   at Minesweeper.Form1.checkdata(String data) in                c:\users\harry\documents\visual studio     2010\Projects\Minesweeper\Minesweeper\Form1.vb:line 139
   at Minesweeper.Login.Receiver() in C:\Users\Harry\Documents\Visual Studio     2010\Projects\Minesweeper\Minesweeper\Login.vb:line 71
   at Minesweeper.Login._Lambda$__1(Object a0) in C:\Users\Harry\Documents\Visual Studio 2010\Projects\Minesweeper\Minesweeper\Login.vb:line 61
   at System.Threading.QueueUserWorkItemCallback.WaitCallback_Context(Object state)
   at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
    at System.Threading.QueueUserWorkItemCallback.System.Threading.IThreadPoolWorkItem.ExecuteWorkItem()
   at System.Threading.ThreadPoolWorkQueue.Dispatch()
   at System.Threading._ThreadPoolWaitCallback.PerformWaitCallback()

---

注意：某些地方的间距错误

此代码不会给出您提供的数据错误：

checkdata("00000000000000000000000000000000000000000000000000000000000000000000000000000000‌​00000000000000000000")

Public Sub checkdata(ByVal data As String)
    If Not data = stringToSend Then
        'Dim loopcount As Integer = 0
        For i As Byte = 0 To 9
            For j As Byte = 0 To 9
                Dim loopcount As Integer = (i.ToString & j.ToString) + 1
                'Dim pineapple As String = pictureboxes(i, j).Tag
                'pictureboxes(i, j).Tag = GetChar(data, 3)

                pictureboxes(i, j).Tag = GetChar(data, loopcount) & "|" & i & ", " & j '***Object reference not set to an instance of an object.***
                formatSenderTag(pictureboxes(i, j).Tag)
                pictureboxes(i, j).ImageLocation = formattedTag(0)
                pictureboxes(i, j).ImageLocation = "0.png"
                'Panel.Controls(pictureboxes(i, j).Tag) = GetChar(data, 3) '.Tag = GetChar(data, 3)

            Next
        Next
    End If
End Sub

查看堆栈跟踪和代码，您缺少登录类中Form1的实例化。我认为这可能是问题所在

尝试将其添加到登录类的开头：

Dim Form1 as New Form1

---

但是当它在pictureboxes（0，0）上运行时会抛出错误，我肯定有0，0作为一个存在的东西。如果我硬编码数字并从该行中删除变量，它也会做同样的事情。

data

和该行的

loopcount

的值是多少？此外，您的代码示例不包括对

子checkdata

的调用。你也可以发布这个吗？这个异常的堆栈跟踪在哪里？如果您分析它，那么它将清楚地给您一行抛出异常的代码。您必须仔细研究跟踪路径。提供跟踪，以便可以为amswer提供数据的值为：0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 Loopcount的值为：1（数据的值是正确的，因为它们都是应用程序中的默认值，因为我没有为测试更改任何内容）其想法是，它将从数据中选择第一个数字，将其指定为pictureboxes数组中第一个事物的标记，然后对第二个事物etcThanks进行某某标记。请参阅上面的代码更新。它不会给出对象引用错误。所以你需要看得更深一些。正如Mukesh所问，堆栈跟踪是什么。这没什么错。你得到的错误是字面上说的。您试图访问一个不存在的对象。你能粘贴你的实际代码吗？根据跟踪，看起来好像是登录接收者发送了呼叫。您在登录类中的何处实例化Form1？你需要添加：暗淡的Form1作为新的Form1哈哈，是的，这似乎已经完成了。你能把这个评论作为一个答案吗？这样我就可以把它标记为最终答案了？谢谢：好的，很高兴听到！我更新了答案：

Dim Form1 as New Form1