Reading txt file line by line in DataGrid View - vb.net

Question

I'm completely new to VB.net and have been given a homework assignment. I need to be able to read certain lines and display them in a DataGridView. I have been able to link my .txt file to the DGV however it reads the whole file as opposed to the specific line. I have 4 buttons: btn1, btn2, btn3, btn4. I want each button to show the respective lines in the text file. After researching on-line for the past week I'm still stuck. If anyone could help me I would really appreciate it.
Text File ("database.txt")
(Line1) c1 c2 c3
(Line2) one 1-1 1-2
(Line3) two 2-2 2-3
(Line4) three 3-2 3-3
(Line5) four 4-2 4-3
Public Class Form1
Private Sub btn1_Click(sender As Object, e As EventArgs) Handles btn1.Click
Dim lines = (From line In IO.File.ReadAllLines("database.txt") _
Select line.Split(CChar(vbTab))).ToArray
For x As Integer = 0 To lines(0).GetUpperBound(0)
DataGridView1.Columns.Add(lines(0)(x), lines(0)(x))
Next
For x As Integer = 1 To lines.GetUpperBound(0)
DataGridView1.Rows.Add(lines(x))
Next
End Sub
End Class

Answer 1

You did not describe the result you get, so I cannot tell what's wrong right now, as I am not on a computer and usually use c++/cli (visual c++). If I have to make a guess, I would say that you fill each file row into one DGV row, but you want just 1 row, not all. Correct?
Anyway, here are some suggestions:
Do you have to read the file on each button click? If not, I would read it once, store the content and fill into the DGV when desired.
Debug your code! Set a breakpoint at the start of the function, step over the code lines, check the variable content.
Split up the code line dim lines into 3 or more separate lines to make it more readable. Also helps at debugging.

Answer 2

I made following assumptions based on what you had in your question:
First line of the file was the column names
The (Line#) was just there for reference and isn't in the actual file
The number in the button name (btn#) was the row index that should be displayed in the DGV
I added a new button to the form that loads the data from the text file, parses it to a datatable and sets the DataGridView1.DataSource to that DataTable. The second method then creates a new datatable and imports the specified row from the main datatable and shows it in the DGV. Of course many will say you should use a DataView with a DataView.RowFilter for this rather than creating a new datatable, however this way works just the same.
Private txtDataTable As DataTable
Private Sub loadFileBtn_Click(sender As Object, e As EventArgs) Handles loadFileBtn.Click
txtDataTable = New DataTable("txtContents")
Dim txtContents As String()
Try
txtContents = IO.File.ReadAllLines("C:\StackOverflow\database.txt")
Catch ex As Exception
MsgBox(ex.Message)
Return
End Try
Dim txtLines As New List(Of String())
txtContents.ToList().ForEach(Sub(x) txtLines.Add(x.Split(CChar(vbTab))))
If txtLines.Count > 0 Then
txtLines.Item(0).ToList.ForEach(Sub(x) txtDataTable.Columns.Add(New DataColumn(x.ToString)))
txtLines.RemoveAt(0)
End If
If txtLines.Count > 0 Then
txtLines.ToList.ForEach(Sub(x) txtDataTable.Rows.Add(x.ToArray))
End If
DataGridView1.DataSource = txtDataTable
End Sub
Private Sub btn_Click(sender As Object, e As EventArgs) Handles btn1.Click, btn2.Click, btn3.Click, btn4.Click
If txtDataTable Is Nothing Then Return
Dim rowIndex As Integer
If Integer.TryParse(DirectCast(sender, Button).Name.Replace("btn", String.Empty), rowIndex) Then
rowIndex -= 1
Else
Return
End If
Dim TempTable As DataTable = txtDataTable.Clone
If rowIndex < txtDataTable.Rows.Count Then
TempTable.ImportRow(txtDataTable.Rows(rowIndex))
End If
DataGridView1.DataSource = TempTable
End Sub