Writing to a file opened in another class

[AA]

Hi,
I am trying to write to a file. I have 3 classes defined. In 1 class
(Test), I have the File open, close utilities. The application is a
console application. I am opening the file in class Test1. I write
something in it. Then I call a sub in class Test2. Here when I try to
write in the file, I am getting error "Object reference not set to an
instance of an object." The error occurs in the WriteToFile sub of
class Test. For some reason Class Test2 does not know that the log file
is open and thit is why the error is coming, I think!
Any other reasons, solutions or workaround?

Regards,
p

<code>
Module Module1

Sub Main()
Dim start_test As New Test1
start_test.run_test()
End Sub

End Module
</code>

<code>
Imports System
Imports System.IO

Public Class Test1
Inherits Test
Dim log_file_name As String = "test1.log"
Sub run_test()
Try
OpenLogFile(log_file_name, False)
log("ii", "pp")
Dim pt As New Test2
pt.run_test1()
Catch ex As Exception
Finally
CloseLogFile()
End Try
End Sub
End Class

Public Class Test2
Inherits Test
Sub run_test1()
Try
log("ii", "phhp")
Catch ex As Exception
Console.WriteLine(ex.Message)
Finally
End Try
End Sub
End Class
</code>

<code>
Imports System
Imports System.IO
Imports System.String
Public Class Test
Dim objStreamWriter As StreamWriter
Public Sub OpenLogFile(ByVal filename As String, ByVal bool As
Boolean)
objStreamWriter = New StreamWriter(filename, bool)
End Sub
Public Sub WriteToFile(ByVal str As String)
Console.WriteLine("in WriteToFile")
objStreamWriter.WriteLine(str)
End Sub

Public Sub CloseLogFile()
objStreamWriter.Close()
End Sub
Public Sub OpenFile(ByVal filename As String, ByVal bool As
Boolean)
objStreamWriter = New StreamWriter(filename, bool)
End Sub

Public Sub CloseFile()
objStreamWriter.Close()
End Sub
Public Sub log(ByVal invoker As String, ByVal methodname As String)
toLog(invoker, methodname)
End Sub
Sub toLog(ByVal MyCallerFile As String, ByVal methodname As String)
Dim str As String
str = MyCallerFile + " " + methodname
WriteToFile(str)
End Sub
End Class
</code>

 

[GhostInAK]

Hello AA,

You forgot to initialize a variable.. or you passed a null reference (Nothing)
to the sub. This error has nothing to do with the state of the file (being
open or not).

-Boo

 

[AA]

Hi,
I got it to work. The problem was I was inheriting classes improperly.
The inheritance should be:
<code>

Public Class Test1
Inherits Test2
.......
End Class

Public Class Test2
Inherits Test
.....
End Class
</code>


Regards,
AA