我正在尝试类似于数据库的程序，它可以添加，搜索，编辑或删除程序创建的文本文件中的记录。在处理第三个表单（Editpg）上的第二个按钮时，我收到一个错误，表示＆＃34; InvalidOperationException未处理：创建表单时出错。有关详细信息，请参阅Exception.InnerException。错误是：对象引用未设置为对象的实例。＆＃34;现在我认为自己是Visual Basic，编程和StackOverflow的初学者，所以我不知道错误是什么以及它们从错误消息中提供的解决方案。谁能帮助我？
主菜单代码（第1版）：
Public Class MainMenu
Private Sub MainMenu_Load(sender As System.Object, e As System.EventArgs) Handles MyBase.Load
Dim path As String = "MyTest.txt"
Dim objReader As New System.IO.StreamReader(path)
Dim TextLine As String = ""
Dim record As String = ""
If My.Computer.FileSystem.FileExists(path) Then
Do While objReader.Peek() <> -1
TextLine = objReader.ReadLine() & vbNewLine
record = record + TextLine
Loop
objReader.Close()
Label2.Text = record
End If
End Sub
Private Sub Button5_Click(sender As System.Object, e As System.EventArgs) Handles Button5.Click
Label2.Top = Label2.Top - 15
End Sub
Private Sub Button6_Click(sender As System.Object, e As System.EventArgs) Handles Button6.Click
Label2.Top = Label2.Top + 15
End Sub
Private Sub Button7_Click(sender As System.Object, e As System.EventArgs) Handles Button7.Click
Addpg.Show()
End Sub
Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click
Searchpg.Show()
End Sub
Private Sub Button3_Click(sender As System.Object, e As System.EventArgs) Handles Button3.Click
Editpg.Show()
End Sub
Private Sub Button4_Click(sender As System.Object, e As System.EventArgs) Handles Button4.Click
Dim path As String = "MyTest.txt"
Dim objReader As New System.IO.StreamReader(path)
Dim TextLine As String = ""
Dim record As String = ""
If My.Computer.FileSystem.FileExists(path) Then
Do While objReader.Peek() <> -1
TextLine = objReader.ReadLine() & vbNewLine
record = record + TextLine
Loop
objReader.Close()
Label2.Text = record
End If
End Sub
Private Sub Button2_Click(sender As System.Object, e As System.EventArgs) Handles Button2.Click
Deletepg.Show()
End Sub
End Class
Editpg代码（第三种形式）:(它没有显示但是有＃34; Imports System.IO＆＃34;＆amp;＆＃34; Imports System.Text＆＃34;代码顶部）
Public Class Editpg
Dim record As String = ""
Dim path As String = "MyTest.txt"
Dim objReader As New System.IO.StreamReader(path)
Dim objReader2 As New System.IO.StreamReader(path)
Dim TextLine As String = ""
Dim idnum As String = NumericUpDown1.Text
Private Sub Button2_Click(sender As System.Object, e As System.EventArgs) Handles Button2.Click
Dim firstpoint As Integer
Dim lastpoint As Integer
Dim result As String = ""
Dim cabin As String
Dim lastn As String
Dim firstn As String
Dim address As String
Dim city As String
Dim zipcode As String
Do While objReader.Peek() <> -1
TextLine = objReader.ReadLine() & vbNewLine
firstpoint = 1
lastpoint = TextLine.IndexOf(")") - firstpoint
result = TextLine.Substring(firstpoint, lastpoint)
If result = idnum Then
record = TextLine
End If
Loop
objReader.Close()
firstpoint = record.IndexOf(")") + 2
lastpoint = record.IndexOf(".") - firstpoint
cabin = record.Substring(firstpoint, lastpoint)
If cabin = "C1" Then
RadioButton1.Checked = True
ElseIf cabin = "C2" Then
RadioButton2.Checked = True
ElseIf cabin = "C3" Then
RadioButton3.Checked = True
ElseIf cabin = "C4" Then
RadioButton4.Checked = True
ElseIf cabin = "C5" Then
RadioButton5.Checked = True
ElseIf cabin = "C6" Then
RadioButton6.Checked = True
ElseIf cabin = "C7" Then
RadioButton7.Checked = True
ElseIf cabin = "C8" Then
RadioButton8.Checked = True
ElseIf cabin = "C9" Then
RadioButton9.Checked = True
ElseIf cabin = "C10" Then
RadioButton10.Checked = True
ElseIf cabin = "UC1" Then
RadioButton11.Checked = True
ElseIf cabin = "UC2" Then
RadioButton12.Checked = True
ElseIf cabin = "UC3 " Then
RadioButton13.Checked = True
ElseIf cabin = "N/A" Then
RadioButton14.Checked = True
End If
firstpoint = record.IndexOf(".") + 2
lastpoint = record.IndexOf(",") - firstpoint
lastn = record.Substring(firstpoint, lastpoint)
TextBox2.Text = lastn
firstpoint = record.IndexOf(",") + 2
lastpoint = record.IndexOf(":") - firstpoint
firstn = record.Substring(firstpoint, lastpoint)
TextBox1.Text = firstn
firstpoint = record.IndexOf(":") + 2
lastpoint = record.IndexOf(",", record.IndexOf(":")) - firstpoint
address = record.Substring(firstpoint, lastpoint)
TextBox3.Text = address
firstpoint = record.IndexOf(",", firstpoint) + 2
lastpoint = record.IndexOf(",", firstpoint) - firstpoint
city = record.Substring(firstpoint, lastpoint)
TextBox4.Text = city
firstpoint = record.IndexOf(",", firstpoint) + 2
lastpoint = record.Length - firstpoint
zipcode = record.Substring(firstpoint, lastpoint)
TextBox5.Text = zipcode
End Sub
Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click
Dim newrecord As String = "(" + idnum + ") "
Dim wholefile As String = ""
Select Case newrecord
Case RadioButton1.Checked
newrecord = newrecord + "C1. "
Case RadioButton2.Checked
newrecord = newrecord + "C2. "
Case RadioButton3.Checked
newrecord = newrecord + "C3. "
Case RadioButton4.Checked
newrecord = newrecord + "C4. "
Case RadioButton5.Checked
newrecord = newrecord + "C5. "
Case RadioButton6.Checked
newrecord = newrecord + "C6. "
Case RadioButton7.Checked
newrecord = newrecord + "C7. "
Case RadioButton8.Checked
newrecord = newrecord + "C8. "
Case RadioButton9.Checked
newrecord = newrecord + "C9. "
Case RadioButton10.Checked
newrecord = newrecord + "C10. "
Case RadioButton11.Checked
newrecord = newrecord + "UC1. "
Case RadioButton12.Checked
newrecord = newrecord + "UC2. "
Case RadioButton13.Checked
newrecord = newrecord + "UC3. "
Case RadioButton14.Checked
newrecord = newrecord + "N/A. "
End Select
record = record + TextBox2.Text + ", " + TextBox1.Text + ": " + TextBox3.Text + ", " + TextBox4.Text + ", " + TextBox5.Text
Do While objReader2.Peek() <> -1
TextLine = objReader2.ReadLine() & vbNewLine
If TextLine = record Then
TextLine = TextLine.Replace(record, newrecord)
End If
wholefile = wholefile + TextLine
Loop
objReader2.Close()
Dim newfile As String = "new.txt"
Dim fs As FileStream = File.Create(newfile)
Dim info As Byte() = New UTF8Encoding(True).GetBytes(wholefile)
fs.Write(info, 0, info.Length)
fs.Close()
My.Computer.FileSystem.DeleteFile(path)
My.Computer.FileSystem.RenameFile(newfile, path)
End Sub
结束班