Why am I getting an error when I try to print the contents of a file I am searching for? - vb.net

Question

Can you help me with searching for and printing a file specified by text in textbox1? I have the following code but textbox1 shows me an error. I don't know if the code is correctly written and functioning right.
First class:
Public Class tisk
'print
Public Shared Function printers()
Dim printThis
Dim strDir As String
Dim strFile As String
Dim Textbox1 As String
strDir = "C:\_Montix a.s. - cloud\iMontix\Testy"
strFile = "C:\_Montix a.s. - cloud\iMontix\Testy\" & Textbox1.text & ".lbe"
If Not fileexprint.FileExists Then
MsgBox("Soubor neexistuje")
printers = False
Else
fileprint.PrintThisfile()
printers = True
End If
End Function
End Class
Second class:
Public Class fileprint
Public Shared Function PrintThisfile()
Dim formname As Long
Dim FileName As String
On Error Resume Next
Dim X As Long
X = Shell(formname, "Print", FileName, 0&)
End Function
End Class
Third class:
Public Class fileexprint
Public Shared Function FileExists()
Dim fname As Boolean
' Returns TRUE if the file exists
Dim X As String
X = Dir(fname)
If X <> "" Then FileExists = True _
Else FileExists = False
End Function
End Class
When I fill a textbox with text, how can I search for a file in the computer using this text and print this file?

Answer 1

Your "Textbox1" is a variable and not actually getting the value from a textbox. If I'm not wrong, I believe you intend to get the value of a textbox and concatenate to form your directory url. You'll first need to add a text box to your windows/web form, give that textbox an id then call that id in your code behind. E.g. You add a text box with id "textbox001", in your code behind you'll do something like "textbox001.text". In your case it'll now be: strFile = "C:_Montix a.s. - cloud\iMontix\Testy\" & textbox001.text & ".lbe". Hope this helps.

Answer 2

Not sure this will fix your issue, but there are some poor practices in that code that are addressed below. This will certainly get you closer than what you have right now.
Public Class tisk
'print
Public Shared Function printers(ByVal fileName As String) As Boolean
Dim basePath As String = "C:\_Montix a.s. - cloud\iMontix\Testy"
Dim filePath As String = IO.Path.Combine(basePath, fileName & ".lbe")
If IO.File.Exists(filePath) Then
fileprint.PrintThisfile(filePath)
Return True
End If
'Don't show a message box here. Do it in the calling code
Return False
End Function
End Class
Public Class fileprint
Public Shared Sub PrintThisfile(ByVal fileName As String)
'Not sure how well this will work, but it has better chances than the original
Dim p As New Process()
p.StartInfo.FileName = fileName
p.StartInfo.Verb = "Print"
p.Start()
End Sub
End Class
One additional comment on the File.Exists() check. It's actually poor practice to check if the file exists here at all. The file system is volatile. It's possible for things to change in the short time between when you check and when you try to use the file. In addition, whether the file exists is only one thing you need to look at. There's also access permissions and whether the file is locked or in use. The better practice is to just try to do whatever you need with the file, and then handle the exception if it fails.