Getting System.IO.IOException - vb.net

Question

I am working with the driving knowledge test program which consist of the multiple choice questions. I am having System.IO.IOException while trying to save the questions in the database file. Few hours earlier the same code was working fine but now it started to show the issue. The error is also mentioning that it cannot access the file and the file is being used by the another process. I also have added the picture to show the error that i faced
AddQuestions.vb
Imports System.IO
Public Class Questions
' Holds question number of question currently being updating or deleting.
Dim currentlyEditingDeleteingQueNo As Integer
Private Sub QuestionForm_Load(sender As System.Object, e As System.EventArgs) Handles MyBase.Load
TXTQuestionNo.Enabled = False
TXTQuestionNo.Text = gloTestQuestions.Count + 1
Fill_Grid()
End Sub
' Insert a new question in array list.
Private Sub BTNAdd_Click(sender As System.Object, e As System.EventArgs) Handles BTNAdd.Click
Dim question As Trivia_Data
question.intQuestionNo = TXTQuestionNo.Text
question.StrQuestion = TXTQuestion.Text
question.StrAnswer1 = TXTAnswer1.Text
question.StrAnswer2 = TXTAnswer2.Text
question.StrAnswer3 = TXTAnswer3.Text
question.StrAnswer4 = TXTAnswer4.Text
question.intCorrectAnswer = Integer.Parse(TXTAnswer5.Text)
gloTestQuestions.Add(question)
Fill_Grid()
MessageBox.Show("Question inserted successfully....")
ClearText()
End Sub
' Clears all text boxes for next question and displays possible question for it.
Private Sub ClearText()
TXTAnswer1.Clear()
TXTAnswer2.Clear()
TXTAnswer3.Clear()
TXTAnswer4.Clear()
TXTAnswer5.Clear()
TXTQuestion.Clear()
TXTQuestionNo.Clear()
TXTQuestionNo.Text = gloTestQuestions.Count + 1
End Sub
' Fills data grid view controls with available questions in a system.
Private Sub Fill_Grid()
Dim dt As DataTable
dt = New DataTable()
dt.Columns.Add("Question Number")
dt.Columns.Add("Question")
dt.Columns.Add("Answer1")
dt.Columns.Add("Answer2")
dt.Columns.Add("Answer3")
dt.Columns.Add("Answer4")
dt.Columns.Add("CorrectAnswer")
Dim question As Trivia_Data
For j = 0 To gloTestQuestions.Count - 1
dt.Rows.Add()
question = CType(gloTestQuestions(j), Trivia_Data)
dt.Rows(j)("Question Number") = question.intQuestionNo.ToString()
dt.Rows(j)("Question") = question.StrQuestion
dt.Rows(j)("Answer1") = question.StrAnswer1
dt.Rows(j)("Answer2") = question.StrAnswer2
dt.Rows(j)("Answer3") = question.StrAnswer3
dt.Rows(j)("Answer4") = question.StrAnswer4
dt.Rows(j)("CorrectAnswer") = question.intCorrectAnswer
Next
'DataGridView1.DataSource = dt
End Sub
' Searchs a question by user supplied question number using binary search technique.
Private Sub BTNFind_Click(sender As System.Object, e As System.EventArgs) Handles BTNFind.Click
Dim totalAddedQuestion As Integer = gloTestQuestions.Count
Dim questionNo = InputBox("Enter the question number that you want to search:")
If questionNo > gloTestQuestions.Count Or questionNo = 0 Then
MessageBox.Show("Question doesn't exist..........")
ClearText()
Exit Sub
Else
Dim compare As New ArrayListIntegerComparere
gloTestQuestions.Sort(compare)
Fill_Grid()
Dim max As Integer
Dim min As Integer
Dim mid As Integer
min = 0
max = totalAddedQuestion - 1
While (max >= min)
mid = (min + max) / 2
Dim question As Trivia_Data = CType(gloTestQuestions(mid), Trivia_Data)
If question.intQuestionNo < questionNo Then
min = mid + 1
ElseIf question.intQuestionNo > questionNo Then
max = mid - 1
Else
TXTAnswer1.Text = question.StrAnswer1
TXTAnswer2.Text = question.StrAnswer2
TXTAnswer3.Text = question.StrAnswer3
TXTAnswer4.Text = question.StrAnswer4
TXTAnswer5.Text = question.intCorrectAnswer
TXTQuestion.Text = question.StrQuestion
TXTQuestionNo.Text = question.intQuestionNo
currentlyEditingDeleteingQueNo = mid
MessageBox.Show("Question found............")
BTNUpdate.Enabled = True
BTNDelete.Enabled = True
Exit Sub
End If
End While
End If
MessageBox.Show("Question doesn't exist.................")
ClearText()
End Sub
' Saves questions in binary file and closes the file after writing operations.
Private Sub BTNSave_Click(sender As System.Object, e As System.EventArgs) Handles BTNSave.Click
Dim file As New FileStream(Directory.GetCurrentDirectory() & "\Question.dat", FileMode.Create, FileAccess.Write)
Dim fileWrite As BinaryWriter = New BinaryWriter(file)
Dim question As Trivia_Data
For i = 0 To gloTestQuestions.Count - 1
question = CType(gloTestQuestions(i), Trivia_Data)
fileWrite.Write(Convert.ToInt16(question.intQuestionNo))
fileWrite.Write(question.StrQuestion)
fileWrite.Write(question.StrAnswer1)
fileWrite.Write(question.StrAnswer2)
fileWrite.Write(question.StrAnswer3)
fileWrite.Write(question.StrAnswer4)
fileWrite.Write(Convert.ToInt16(question.intCorrectAnswer))
Next
fileWrite.Close()
file.Close()
MessageBox.Show("Questions saved in file successfully..........")
End Sub
' Updates exisitng question as per newly provided values.
Private Sub BTNUpdate_Click(sender As System.Object, e As System.EventArgs) Handles BTNUpdate.Click
Dim question As Trivia_Data = CType(gloTestQuestions(currentlyEditingDeleteingQueNo), Trivia_Data)
question.StrAnswer1 = TXTAnswer1.Text
question.StrAnswer2 = TXTAnswer2.Text
question.StrAnswer3 = TXTAnswer3.Text
question.StrAnswer4 = TXTAnswer4.Text
question.intCorrectAnswer = Integer.Parse(TXTAnswer5.Text)
question.StrQuestion = TXTQuestion.Text
gloTestQuestions(currentlyEditingDeleteingQueNo) = question
MessageBox.Show("Question updated successfully...................")
BTNUpdate.Enabled = False
BTNDelete.Enabled = False
ClearText()
Fill_Grid()
End Sub
' Deletes a current question from the arraylist.
Private Sub BTNDelete_Click(sender As System.Object, e As System.EventArgs) Handles BTNDelete.Click
gloTestQuestions.RemoveAt(currentlyEditingDeleteingQueNo)
Fill_Grid()
ClearText()
MessageBox.Show("Question removed successfully.....")
BTNDelete.Enabled = False
BTNUpdate.Enabled = False
End Sub
' Closes the Question form
Private Sub BTNClose_Click(sender As System.Object, e As System.EventArgs) Handles BTNClose.Click
Me.Close()
End Sub
End Class

Answer 1

Did you encounter any exceptions during testing which may have caused the file not being correctly closed (file.close()) by your own application?
Do you have the file (Question.dat) open in another program?
Does an instance of your application still run and keeps the file open?
When dealing with this sort of operations it is better to rewrite your code something like this :
EDIT VB .NET (pseudo code)
Try
Using file As New File
' your code...
End Using
Catch exception As Exception
' log and/or show to user...
Finally
' your code...
file.Close()
End Try
Original C# code
try{
// If the file class implements IDisposable
using(File file = new file()){
// your code...
...
}
}
catch(Exception ex){
// log and/or show to user
}
finally{
file.close();
}
It is hard to say what process/application has the file in use or locked so for now I should say, close and reopen Visual Studio or even worse restart Windows.