Errors How to Catch them in VB.Net

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Always Remember:
Error handling is a very important part of any application.

• In VB.Net, the error mechanism is a concept of exceptions that can be thrown to raise an error and caught when the error is handled properly.
• If you don’t have any error handling in your code and an error occurs, your users receive a message about an unhandled  exception, and then the program may terminate.
• The unhandled exception could cause users to lose the data that they were working.
• The Visual Basic offers a great way to organize blocks of code in a structure that handles errors by means of structured error handling.
• This mechanism is incorporated with the Try… Catch… Finally block and helps you to incorporate error handling into your programs.
• Essentially you execute the code that might throw an exception in the Try block, and you handle the errors in the Catch block.
• The Finally block, which is optional, is always executed if present and helps you cleanup your code.
• Usually in the Finally block you keep your dispose and close methods like connection.Close() that unsures that your connection is closed no matter what error you get in the Try block.

Here is example:

[vbnet]

Try
conn.Open()
dbreader = cmd.ExecuteReader()
obj.rows.clear()
Select Case caseswitch
Case "StudentLoad"
Do While dbreader.Read = True ' Does something with the reader
obj.rows.add(False, dbreader(0), dbreader(1), dbreader(2), dbreader(3))
Loop

End Select
Catch ex As Exception
'with this it may display the error
End Try
conn.Close() 'this code will be always executed

[/vbnet]

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