本文介绍了有人能帮我解决这个错误“NullReferenceException 未处理"吗?的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
我使用的是 Visual Studio 2013,这部分代码是关于讲师发布咨询时间表的.但是当我点击发布按钮时,它显示了这个错误.这是我的代码..
I'm using Visual Studio 2013, this part of the code is about lecturer publishing consultation schedule. But when i clicked the publish button, it shows me this error. Here's my code..
Imports System.Data.OleDb
公开课咨询时间表
Private Sub publishbutton_Click(sender As Object, e As EventArgs) Handles publishbutton.Click
Dim label As String = "Label"
Dim sql As String
Dim cmd As OleDbCommand
Dim time1 As String = vbNull
Dim time2 As String = vbNull
Dim time3 As String = vbNull
Dim time4 As String = vbNull
Dim day1 As String = Nothing
Dim day2 As String = vbNull
Dim day3 As String = vbNull
Dim day4 As String = vbNull
Dim day5 As String = vbNull
Dim available1 As String = Nothing
Dim available2 As String = vbNull
Dim available3 As String = vbNull
Dim available4 As String = vbNull
For i = 11 To 15
time1 = Label7.Text
For k = 16 To 20
time2 = Label8.Text
For t = 21 To 25
time3 = Label9.Text
For u = 26 To 30
time4 = Label10.Text
Next
Next
Next
Next
For i = 11 To 30
If (i = 11) Then
day1 = Label2.Text
If (Me.Controls(label & i.ToString).BackColor = Color.Lime) Then
available1 = "Available"
Else
available1 = "Unavailable"
End If
ElseIf (i = 16) Then
day1 = Label2.Text
If (Me.Controls(label & i.ToString).BackColor = Color.Lime) Then
available2 = "Available"
Else
available2 = "Unavailable"
End If
ElseIf (i = 21) Then
day1 = Label2.Text
If (Me.Controls(label & i.ToString).BackColor = Color.Lime) Then
available3 = "Available"
Else
available3 = "Unavailable"
End If
ElseIf (i = 26) Then
day1 = Label2.Text
If (Me.Controls(label & i.ToString).BackColor = Color.Lime) Then
available4 = "Available"
Else
available4 = "Unavailable"
End If
End If
Next
For k = 11 To 30
If (k = 12) Then
day2 = Label3.Text
ElseIf (k = 17) Then
day2 = Label3.Text
ElseIf (k = 22) Then
day2 = Label3.Text
ElseIf (k = 27) Then
day2 = Label3.Text
End If
Next
For t = 11 To 30
If (t = 13) Then
day3 = Label4.Text
ElseIf (t = 18) Then
day3 = Label4.Text
ElseIf (t = 23) Then
day3 = Label4.Text
ElseIf (t = 28) Then
day3 = Label4.Text
End If
Next
For u = 11 To 30
If (u = 14) Then
day4 = Label5.Text
ElseIf (u = 19) Then
day4 = Label5.Text
ElseIf (u = 24) Then
day4 = Label5.Text
ElseIf (u = 29) Then
day4 = Label5.Text
End If
Next
For y = 11 To 30
If (y = 15) Then
day5 = Label6.Text
ElseIf (y = 20) Then
day5 = Label6.Text
ElseIf (y = 25) Then
day5 = Label6.Text
ElseIf (y = 30) Then
day5 = Label6.Text
End If
Next
Dim conn = New OleDbConnection("Provider=Microsoft.ACE.OLEDB.12.0;Data Source=scheduledatabase.accdb;Persist Security Info=False;")
sql = "INSERT INTO consultationschedule(Time, Day, Available)VALUES(@Time,@Day,@Available)"
conn.Open()
cmd = New OleDbCommand(sql, conn)
cmd.Parameters.AddWithValue("@Time", time1)
cmd.Parameters.AddWithValue("@Day", day1)
cmd.Parameters.AddWithValue("@Available", available1)
'cmd.ExecuteNonQuery()
Dim f As Integer = cmd.ExecuteNonQuery()
If (f >= 1) Then
ToolStrip1.Text = f.ToString & " record added successfully"
Else
ToolStrip1.Text = "Unable to add record"
End If
MessageBox.Show("User Widrawed", "Widrawed", MessageBoxButtons.OK, MessageBoxIcon.Information)
conn.Close()
End Sub
推荐答案
Me.Controls(label & i.ToString).BackColor = Color.Lime
与
Me.Controls("Label11").BackColor = Color.Lime
...
Me.Controls("Label30").BackColor = Color.Lime
你有 30 个编号的标签吗?
Do you have 30 numbered labels?
你可以这样做
If Not Me.Controls(label & i.ToString) Is Nothing Then
Me.Controls(label & i.ToString).BackColor = Color.Lime
End If
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