Try Catch question

[Woody Splawn]

I have a try catch statement in a fucntion that is supposed to return a true
or a false

My code looks like this:

Try
mySqlConnection .Open()
Dim Da1 As New SqlDataAdapter( "Select JnlType, Description from
JnlType", mySqlConnection )
Dim Ds As New DataSet("X")
Da1.Fill(Ds)
Catch
MsgBox("There was a problem filling the Dataset for Lookup table
for JnlType")
Return False
Finally
If mySqlConnection .State = ConnectionState .Open Then
mySqlConnection .Close()
End If
End Try

My question is this: Is the Try Catch code smart enough to run the Finally
statment after the MsgBox and then return false or do I need to write the
code some other way. This is what I want it to do but I am not sure I have
it written correctly.

[William Ryan eMVP]

Re: Try Catch question

Finally will always be executed and yes, it will still return false the way
you wrote it.
"Woody Splawn" <woody@splawns. com> wrote in message
news:u7eMoqr6DH A.2300@TK2MSFTN GP10.phx.gbl...[color=blue]
> I have a try catch statement in a fucntion that is supposed to return a[/color]
true[color=blue]
> or a false
>
> My code looks like this:
>
> Try
> mySqlConnection .Open()
> Dim Da1 As New SqlDataAdapter( "Select JnlType, Description[/color]
from[color=blue]
> JnlType", mySqlConnection )
> Dim Ds As New DataSet("X")
> Da1.Fill(Ds)
> Catch
> MsgBox("There was a problem filling the Dataset for Lookup[/color]
table[color=blue]
> for JnlType")
> Return False
> Finally
> If mySqlConnection .State = ConnectionState .Open Then
> mySqlConnection .Close()
> End If
> End Try
>
> My question is this: Is the Try Catch code smart enough to run the[/color]
Finally[color=blue]
> statment after the MsgBox and then return false or do I need to write the
> code some other way. This is what I want it to do but I am not sure I[/color]
have[color=blue]
> it written correctly.
>
>
>[/color]

[Tom Leylan]

Re: Try Catch question

William... I believe we need to clarify something. It isn't going to
return FALSE because of the way he wrote it. It is going to return FALSE
because it ends up FALSE when no return value has been set.


Woody... I don't think you want it to just "accidental ly" work. Test it
yourself but (as part of the test) have a function return an integer so you
can get more than 2 return values.

Unless I'm greatly mistaken it works as follows:

You want two return statements in your code: Return True in the Try block
and Return False after the End Try. With no return in Catch or Finally.

If there is no error it will return the value in the Try block (TRUE) if
there is an error the Catch block executes, the the Finally and you will
return the value of the Return statement (FALSE).

Interestingly even if you place a return statement in the Catch block it
will not be returned. Either the Try return works or the final return does.

Test it out...
Tom



"William Ryan eMVP" <bill@NoSp4m.de vbuzz.com> wrote in message
news:uFrMFxr6DH A.2952@TK2MSFTN GP09.phx.gbl...[color=blue]
> Finally will always be executed and yes, it will still return false the[/color]
way[color=blue]
> you wrote it.
> "Woody Splawn" <woody@splawns. com> wrote in message
> news:u7eMoqr6DH A.2300@TK2MSFTN GP10.phx.gbl...[color=green]
> > I have a try catch statement in a fucntion that is supposed to return a[/color]
> true[color=green]
> > or a false
> >
> > My code looks like this:
> >
> > Try
> > mySqlConnection .Open()
> > Dim Da1 As New SqlDataAdapter( "Select JnlType, Description[/color]
> from[color=green]
> > JnlType", mySqlConnection )
> > Dim Ds As New DataSet("X")
> > Da1.Fill(Ds)
> > Catch
> > MsgBox("There was a problem filling the Dataset for Lookup[/color]
> table[color=green]
> > for JnlType")
> > Return False
> > Finally
> > If mySqlConnection .State = ConnectionState .Open Then
> > mySqlConnection .Close()
> > End If
> > End Try
> >
> > My question is this: Is the Try Catch code smart enough to run the[/color]
> Finally[color=green]
> > statment after the MsgBox and then return false or do I need to write[/color][/color]
the[color=blue][color=green]
> > code some other way. This is what I want it to do but I am not sure I[/color]
> have[color=green]
> > it written correctly.
> >
> >
> >[/color]
>
>[/color]

[William Ryan eMVP]

Re: Try Catch question

Tom:

Good call, and yes you're absolutely correct. I realize my answer may have
been misleading -- I was answering it in the context of if an exception was
caused b/c it seemed he was asking about the behavior of Finally. However,
if you don't return a value in this instance, it will in fact return false.
That's more a function of how VB.NET can allow you to not explicitly return
a value in a function but you have a good point nonetheless.

I'll be more clear next time.

bill
"Tom Leylan" <gee@iamtiredof spam.com> wrote in message
news:eOf9qQs6DH A.1936@TK2MSFTN GP12.phx.gbl...[color=blue]
> William... I believe we need to clarify something. It isn't going to
> return FALSE because of the way he wrote it. It is going to return FALSE
> because it ends up FALSE when no return value has been set.
>
>
> Woody... I don't think you want it to just "accidental ly" work. Test it
> yourself but (as part of the test) have a function return an integer so[/color]
you[color=blue]
> can get more than 2 return values.
>
> Unless I'm greatly mistaken it works as follows:
>
> You want two return statements in your code: Return True in the Try block
> and Return False after the End Try. With no return in Catch or Finally.
>
> If there is no error it will return the value in the Try block (TRUE) if
> there is an error the Catch block executes, the the Finally and you will
> return the value of the Return statement (FALSE).
>
> Interestingly even if you place a return statement in the Catch block it
> will not be returned. Either the Try return works or the final return[/color]
does.[color=blue]
>
> Test it out...
> Tom
>
>
>
> "William Ryan eMVP" <bill@NoSp4m.de vbuzz.com> wrote in message
> news:uFrMFxr6DH A.2952@TK2MSFTN GP09.phx.gbl...[color=green]
> > Finally will always be executed and yes, it will still return false the[/color]
> way[color=green]
> > you wrote it.
> > "Woody Splawn" <woody@splawns. com> wrote in message
> > news:u7eMoqr6DH A.2300@TK2MSFTN GP10.phx.gbl...[color=darkred]
> > > I have a try catch statement in a fucntion that is supposed to return[/color][/color][/color]
a[color=blue][color=green]
> > true[color=darkred]
> > > or a false
> > >
> > > My code looks like this:
> > >
> > > Try
> > > mySqlConnection .Open()
> > > Dim Da1 As New SqlDataAdapter( "Select JnlType, Description[/color]
> > from[color=darkred]
> > > JnlType", mySqlConnection )
> > > Dim Ds As New DataSet("X")
> > > Da1.Fill(Ds)
> > > Catch
> > > MsgBox("There was a problem filling the Dataset for Lookup[/color]
> > table[color=darkred]
> > > for JnlType")
> > > Return False
> > > Finally
> > > If mySqlConnection .State = ConnectionState .Open Then
> > > mySqlConnection .Close()
> > > End If
> > > End Try
> > >
> > > My question is this: Is the Try Catch code smart enough to run the[/color]
> > Finally[color=darkred]
> > > statment after the MsgBox and then return false or do I need to write[/color][/color]
> the[color=green][color=darkred]
> > > code some other way. This is what I want it to do but I am not sure I[/color]
> > have[color=darkred]
> > > it written correctly.
> > >
> > >
> > >[/color]
> >
> >[/color]
>
>[/color]

[Brian]

Re: Try Catch question

Woody, you wrote it correctly. It will return False because all the code in
your catch block will run. It doesn't matter if you have a Finally or not. I
wouldn't change a thing. It works perfectly.


"Woody Splawn" <woody@splawns. com> wrote in message
news:u7eMoqr6DH A.2300@TK2MSFTN GP10.phx.gbl...[color=blue]
> I have a try catch statement in a fucntion that is supposed to return a[/color]
true[color=blue]
> or a false
>
> My code looks like this:
>
> Try
> mySqlConnection .Open()
> Dim Da1 As New SqlDataAdapter( "Select JnlType, Description[/color]
from[color=blue]
> JnlType", mySqlConnection )
> Dim Ds As New DataSet("X")
> Da1.Fill(Ds)
> Catch
> MsgBox("There was a problem filling the Dataset for Lookup[/color]
table[color=blue]
> for JnlType")
> Return False
> Finally
> If mySqlConnection .State = ConnectionState .Open Then
> mySqlConnection .Close()
> End If
> End Try
>
> My question is this: Is the Try Catch code smart enough to run the[/color]
Finally[color=blue]
> statment after the MsgBox and then return false or do I need to write the
> code some other way. This is what I want it to do but I am not sure I[/color]
have[color=blue]
> it written correctly.
>
>
>[/color]

[Brian]

Re: Try Catch question

Oops, I would change one thing: Put a Return True after Da1.Fill(Ds). Then
it should work correctly.

Try
mySqlConnection .Open()
Dim Da1 As New SqlDataAdapter( "Select JnlType, Description from
JnlType", mySqlConnection )
Dim Ds As New DataSet("X")
Da1.Fill(Ds)
Return True <-------------------ADD THIS
Catch
MsgBox("There was a problem filling the Dataset for Lookup table
for JnlType")
Return False
Finally
If mySqlConnection .State = ConnectionState .Open Then
mySqlConnection .Close()
End If
End Try


"Brian" <nospam@prairie .lakes.com> wrote in message
news:1020n4u6oc 3sf8c@corp.supe rnews.com...[color=blue]
> Woody, you wrote it correctly. It will return False because all the code[/color]
in[color=blue]
> your catch block will run. It doesn't matter if you have a Finally or not.[/color]
I[color=blue]
> wouldn't change a thing. It works perfectly.
>
>
> "Woody Splawn" <woody@splawns. com> wrote in message
> news:u7eMoqr6DH A.2300@TK2MSFTN GP10.phx.gbl...[color=green]
> > I have a try catch statement in a fucntion that is supposed to return a[/color]
> true[color=green]
> > or a false
> >
> > My code looks like this:
> >
> > Try
> > mySqlConnection .Open()
> > Dim Da1 As New SqlDataAdapter( "Select JnlType, Description[/color]
> from[color=green]
> > JnlType", mySqlConnection )
> > Dim Ds As New DataSet("X")
> > Da1.Fill(Ds)
> > Catch
> > MsgBox("There was a problem filling the Dataset for Lookup[/color]
> table[color=green]
> > for JnlType")
> > Return False
> > Finally
> > If mySqlConnection .State = ConnectionState .Open Then
> > mySqlConnection .Close()
> > End If
> > End Try
> >
> > My question is this: Is the Try Catch code smart enough to run the[/color]
> Finally[color=green]
> > statment after the MsgBox and then return false or do I need to write[/color][/color]
the[color=blue][color=green]
> > code some other way. This is what I want it to do but I am not sure I[/color]
> have[color=green]
> > it written correctly.
> >
> >
> >[/color]
>
>[/color]

[Tom Leylan]

Re: Try Catch question

Test it Brian... your I believe you will find that your Return False doesn't
execute.


"Brian" <nospam@prairie .lakes.com> wrote in message
news:1020njo2tq 0v786@corp.supe rnews.com...[color=blue]
> Oops, I would change one thing: Put a Return True after Da1.Fill(Ds). Then
> it should work correctly.
>
> Try
> mySqlConnection .Open()
> Dim Da1 As New SqlDataAdapter( "Select JnlType, Description[/color]
from[color=blue]
> JnlType", mySqlConnection )
> Dim Ds As New DataSet("X")
> Da1.Fill(Ds)
> Return True <-------------------ADD THIS
> Catch
> MsgBox("There was a problem filling the Dataset for Lookup table
> for JnlType")
> Return False
> Finally
> If mySqlConnection .State = ConnectionState .Open Then
> mySqlConnection .Close()
> End If
> End Try
>
>
> "Brian" <nospam@prairie .lakes.com> wrote in message
> news:1020n4u6oc 3sf8c@corp.supe rnews.com...[color=green]
> > Woody, you wrote it correctly. It will return False because all the code[/color]
> in[color=green]
> > your catch block will run. It doesn't matter if you have a Finally or[/color][/color]
not.[color=blue]
> I[color=green]
> > wouldn't change a thing. It works perfectly.
> >
> >
> > "Woody Splawn" <woody@splawns. com> wrote in message
> > news:u7eMoqr6DH A.2300@TK2MSFTN GP10.phx.gbl...[color=darkred]
> > > I have a try catch statement in a fucntion that is supposed to return[/color][/color][/color]
a[color=blue][color=green]
> > true[color=darkred]
> > > or a false
> > >
> > > My code looks like this:
> > >
> > > Try
> > > mySqlConnection .Open()
> > > Dim Da1 As New SqlDataAdapter( "Select JnlType, Description[/color]
> > from[color=darkred]
> > > JnlType", mySqlConnection )
> > > Dim Ds As New DataSet("X")
> > > Da1.Fill(Ds)
> > > Catch
> > > MsgBox("There was a problem filling the Dataset for Lookup[/color]
> > table[color=darkred]
> > > for JnlType")
> > > Return False
> > > Finally
> > > If mySqlConnection .State = ConnectionState .Open Then
> > > mySqlConnection .Close()
> > > End If
> > > End Try
> > >
> > > My question is this: Is the Try Catch code smart enough to run the[/color]
> > Finally[color=darkred]
> > > statment after the MsgBox and then return false or do I need to write[/color][/color]
> the[color=green][color=darkred]
> > > code some other way. This is what I want it to do but I am not sure I[/color]
> > have[color=darkred]
> > > it written correctly.
> > >
> > >
> > >[/color]
> >
> >[/color]
>
>[/color]

[Brian]

Re: Try Catch question

I did. It worked perfectly. Now it's your turn to test it. Use the debugger
to step thru the code.

Private Function Test() As Boolean
Dim g As Integer = 5
Try
g \= 0 '<----------Force an exception , will return false.
Then change it to g \= 1 will return True
Return True
Catch ex As Exception
MessageBox.Show ("Caught")
Return False
Finally
MessageBox.Show ("Finally")
End Try

End Function



"Tom Leylan" <gee@iamtiredof spam.com> wrote in message
news:OG%23lVvs6 DHA.488@TK2MSFT NGP12.phx.gbl.. .[color=blue]
> Test it Brian... your I believe you will find that your Return False[/color]
doesn't[color=blue]
> execute.
>
>
> "Brian" <nospam@prairie .lakes.com> wrote in message
> news:1020njo2tq 0v786@corp.supe rnews.com...[color=green]
> > Oops, I would change one thing: Put a Return True after Da1.Fill(Ds).[/color][/color]
Then[color=blue][color=green]
> > it should work correctly.
> >
> > Try
> > mySqlConnection .Open()
> > Dim Da1 As New SqlDataAdapter( "Select JnlType, Description[/color]
> from[color=green]
> > JnlType", mySqlConnection )
> > Dim Ds As New DataSet("X")
> > Da1.Fill(Ds)
> > Return True <-------------------ADD THIS
> > Catch
> > MsgBox("There was a problem filling the Dataset for Lookup[/color][/color]
table[color=blue][color=green]
> > for JnlType")
> > Return False
> > Finally
> > If mySqlConnection .State = ConnectionState .Open Then
> > mySqlConnection .Close()
> > End If
> > End Try
> >
> >
> > "Brian" <nospam@prairie .lakes.com> wrote in message
> > news:1020n4u6oc 3sf8c@corp.supe rnews.com...[color=darkred]
> > > Woody, you wrote it correctly. It will return False because all the[/color][/color][/color]
code[color=blue][color=green]
> > in[color=darkred]
> > > your catch block will run. It doesn't matter if you have a Finally or[/color][/color]
> not.[color=green]
> > I[color=darkred]
> > > wouldn't change a thing. It works perfectly.
> > >
> > >
> > > "Woody Splawn" <woody@splawns. com> wrote in message
> > > news:u7eMoqr6DH A.2300@TK2MSFTN GP10.phx.gbl...
> > > > I have a try catch statement in a fucntion that is supposed to[/color][/color][/color]
return[color=blue]
> a[color=green][color=darkred]
> > > true
> > > > or a false
> > > >
> > > > My code looks like this:
> > > >
> > > > Try
> > > > mySqlConnection .Open()
> > > > Dim Da1 As New SqlDataAdapter( "Select JnlType,[/color][/color][/color]
Description[color=blue][color=green][color=darkred]
> > > from
> > > > JnlType", mySqlConnection )
> > > > Dim Ds As New DataSet("X")
> > > > Da1.Fill(Ds)
> > > > Catch
> > > > MsgBox("There was a problem filling the Dataset for[/color][/color][/color]
Lookup[color=blue][color=green][color=darkred]
> > > table
> > > > for JnlType")
> > > > Return False
> > > > Finally
> > > > If mySqlConnection .State = ConnectionState .Open Then
> > > > mySqlConnection .Close()
> > > > End If
> > > > End Try
> > > >
> > > > My question is this: Is the Try Catch code smart enough to run the
> > > Finally
> > > > statment after the MsgBox and then return false or do I need to[/color][/color][/color]
write[color=blue][color=green]
> > the[color=darkred]
> > > > code some other way. This is what I want it to do but I am not sure[/color][/color][/color]
I[color=blue][color=green][color=darkred]
> > > have
> > > > it written correctly.
> > > >
> > > >
> > > >
> > >
> > >[/color]
> >
> >[/color]
>
>[/color]

[Tom Leylan]

Re: Try Catch question

Seriously I wouldn't have mentioned you trying it if I hadn't :-) I didn't
step through it with the debugger but I did set return values. This time
however it is returning the return value in the catch block... I mentioned
in another reply that it didn't matter. Can't imagine what I did
differently.

Let me post my code and Woody can decide what he prefers. While it works as
you posted it something seems odd about "return" which is supposed to exit
immediately suddenly not exiting. Clearly the error handler has deferred it
but perhaps that is why Woody was uncertain. What I've done is simply use
the Function name which as we know will return the value and does not cause
an immediate exit (in the normal case) so it behaves identically whether or
not an error has occurred.

You are correct however that it works fine the way you posted it. I don't
know what I did in my first test...
Tom


Public Function ErrorSub() As Boolean

Try
Throw New System.Exceptio n("error")
ErrorSub = True

Catch ex As Exception
MsgBox("catch", MsgBoxStyle.OKO nly, "error")
ErrorSub = False

Finally
MsgBox("finally ", MsgBoxStyle.OKO nly, "error")

End Try

End Function



"Brian" <nospam@prairie .lakes.com> wrote in message
news:1020prqf2t 3cidd@corp.supe rnews.com...[color=blue]
> I did. It worked perfectly. Now it's your turn to test it. Use the[/color]
debugger[color=blue]
> to step thru the code.
>
> Private Function Test() As Boolean
> Dim g As Integer = 5
> Try
> g \= 0 '<----------Force an exception , will return false.
> Then change it to g \= 1 will return True
> Return True
> Catch ex As Exception
> MessageBox.Show ("Caught")
> Return False
> Finally
> MessageBox.Show ("Finally")
> End Try
>
> End Function
>
>
>
> "Tom Leylan" <gee@iamtiredof spam.com> wrote in message
> news:OG%23lVvs6 DHA.488@TK2MSFT NGP12.phx.gbl.. .[color=green]
> > Test it Brian... your I believe you will find that your Return False[/color]
> doesn't[color=green]
> > execute.
> >
> >
> > "Brian" <nospam@prairie .lakes.com> wrote in message
> > news:1020njo2tq 0v786@corp.supe rnews.com...[color=darkred]
> > > Oops, I would change one thing: Put a Return True after Da1.Fill(Ds).[/color][/color]
> Then[color=green][color=darkred]
> > > it should work correctly.
> > >
> > > Try
> > > mySqlConnection .Open()
> > > Dim Da1 As New SqlDataAdapter( "Select JnlType, Description[/color]
> > from[color=darkred]
> > > JnlType", mySqlConnection )
> > > Dim Ds As New DataSet("X")
> > > Da1.Fill(Ds)
> > > Return True <-------------------ADD THIS
> > > Catch
> > > MsgBox("There was a problem filling the Dataset for Lookup[/color][/color]
> table[color=green][color=darkred]
> > > for JnlType")
> > > Return False
> > > Finally
> > > If mySqlConnection .State = ConnectionState .Open Then
> > > mySqlConnection .Close()
> > > End If
> > > End Try
> > >
> > >
> > > "Brian" <nospam@prairie .lakes.com> wrote in message
> > > news:1020n4u6oc 3sf8c@corp.supe rnews.com...
> > > > Woody, you wrote it correctly. It will return False because all the[/color][/color]
> code[color=green][color=darkred]
> > > in
> > > > your catch block will run. It doesn't matter if you have a Finally[/color][/color][/color]
or[color=blue][color=green]
> > not.[color=darkred]
> > > I
> > > > wouldn't change a thing. It works perfectly.
> > > >
> > > >
> > > > "Woody Splawn" <woody@splawns. com> wrote in message
> > > > news:u7eMoqr6DH A.2300@TK2MSFTN GP10.phx.gbl...
> > > > > I have a try catch statement in a fucntion that is supposed to[/color][/color]
> return[color=green]
> > a[color=darkred]
> > > > true
> > > > > or a false
> > > > >
> > > > > My code looks like this:
> > > > >
> > > > > Try
> > > > > mySqlConnection .Open()
> > > > > Dim Da1 As New SqlDataAdapter( "Select JnlType,[/color][/color]
> Description[color=green][color=darkred]
> > > > from
> > > > > JnlType", mySqlConnection )
> > > > > Dim Ds As New DataSet("X")
> > > > > Da1.Fill(Ds)
> > > > > Catch
> > > > > MsgBox("There was a problem filling the Dataset for[/color][/color]
> Lookup[color=green][color=darkred]
> > > > table
> > > > > for JnlType")
> > > > > Return False
> > > > > Finally
> > > > > If mySqlConnection .State = ConnectionState .Open Then
> > > > > mySqlConnection .Close()
> > > > > End If
> > > > > End Try
> > > > >
> > > > > My question is this: Is the Try Catch code smart enough to run[/color][/color][/color]
the[color=blue][color=green][color=darkred]
> > > > Finally
> > > > > statment after the MsgBox and then return false or do I need to[/color][/color]
> write[color=green][color=darkred]
> > > the
> > > > > code some other way. This is what I want it to do but I am not[/color][/color][/color]
sure[color=blue]
> I[color=green][color=darkred]
> > > > have
> > > > > it written correctly.
> > > > >
> > > > >
> > > > >
> > > >
> > > >
> > >
> > >[/color]
> >
> >[/color]
>
>[/color]

[Tom Leylan]

Re: Try Catch question

Turns out it wasn't such a good call. I swear I tested the code but
"something" mixed me up.

The Return statement is deferred until after the finally statement
executes... the line is executed but it doesn't actually exit at that point.
So anyway, it would work but I posted slightly different syntax (using the
function name) which makes it clearer (to me) that it is only assigning the
value and can't possibly return at that point.

Tom


"William Ryan eMVP" <bill@NoSp4m.de vbuzz.com> wrote in message
news:O3tDues6DH A.1816@TK2MSFTN GP12.phx.gbl...[color=blue]
> Tom:
>
> Good call, and yes you're absolutely correct. I realize my answer may[/color]
have[color=blue]
> been misleading -- I was answering it in the context of if an exception[/color]
was[color=blue]
> caused b/c it seemed he was asking about the behavior of Finally.[/color]
However,[color=blue]
> if you don't return a value in this instance, it will in fact return[/color]
false.[color=blue]
> That's more a function of how VB.NET can allow you to not explicitly[/color]
return[color=blue]
> a value in a function but you have a good point nonetheless.
>
> I'll be more clear next time.
>
> bill
> "Tom Leylan" <gee@iamtiredof spam.com> wrote in message
> news:eOf9qQs6DH A.1936@TK2MSFTN GP12.phx.gbl...[color=green]
> > William... I believe we need to clarify something. It isn't going to
> > return FALSE because of the way he wrote it. It is going to return[/color][/color]
FALSE[color=blue][color=green]
> > because it ends up FALSE when no return value has been set.
> >
> >
> > Woody... I don't think you want it to just "accidental ly" work. Test it
> > yourself but (as part of the test) have a function return an integer so[/color]
> you[color=green]
> > can get more than 2 return values.
> >
> > Unless I'm greatly mistaken it works as follows:
> >
> > You want two return statements in your code: Return True in the Try[/color][/color]
block[color=blue][color=green]
> > and Return False after the End Try. With no return in Catch or Finally.
> >
> > If there is no error it will return the value in the Try block (TRUE) if
> > there is an error the Catch block executes, the the Finally and you will
> > return the value of the Return statement (FALSE).
> >
> > Interestingly even if you place a return statement in the Catch block it
> > will not be returned. Either the Try return works or the final return[/color]
> does.[color=green]
> >
> > Test it out...
> > Tom
> >
> >
> >
> > "William Ryan eMVP" <bill@NoSp4m.de vbuzz.com> wrote in message
> > news:uFrMFxr6DH A.2952@TK2MSFTN GP09.phx.gbl...[color=darkred]
> > > Finally will always be executed and yes, it will still return false[/color][/color][/color]
the[color=blue][color=green]
> > way[color=darkred]
> > > you wrote it.
> > > "Woody Splawn" <woody@splawns. com> wrote in message
> > > news:u7eMoqr6DH A.2300@TK2MSFTN GP10.phx.gbl...
> > > > I have a try catch statement in a fucntion that is supposed to[/color][/color][/color]
return[color=blue]
> a[color=green][color=darkred]
> > > true
> > > > or a false
> > > >
> > > > My code looks like this:
> > > >
> > > > Try
> > > > mySqlConnection .Open()
> > > > Dim Da1 As New SqlDataAdapter( "Select JnlType,[/color][/color][/color]
Description[color=blue][color=green][color=darkred]
> > > from
> > > > JnlType", mySqlConnection )
> > > > Dim Ds As New DataSet("X")
> > > > Da1.Fill(Ds)
> > > > Catch
> > > > MsgBox("There was a problem filling the Dataset for[/color][/color][/color]
Lookup[color=blue][color=green][color=darkred]
> > > table
> > > > for JnlType")
> > > > Return False
> > > > Finally
> > > > If mySqlConnection .State = ConnectionState .Open Then
> > > > mySqlConnection .Close()
> > > > End If
> > > > End Try
> > > >
> > > > My question is this: Is the Try Catch code smart enough to run the
> > > Finally
> > > > statment after the MsgBox and then return false or do I need to[/color][/color][/color]
write[color=blue][color=green]
> > the[color=darkred]
> > > > code some other way. This is what I want it to do but I am not sure[/color][/color][/color]
I[color=blue][color=green][color=darkred]
> > > have
> > > > it written correctly.
> > > >
> > > >
> > > >
> > >
> > >[/color]
> >
> >[/color]
>
>[/color]

[William Ryan eMVP]

Re: Try Catch question

Tom:

Your point is still correct, namely that if you don't specify a return type
in your function, it's coming back null. If you look at the original
question and context, it will return false if an exception is thrown.
VB.NET is 'smart' enough to fire the messagebox, return false and execute
the code in the finally statement.

I guess another point worth bringing up is that Finally blocks aren't well
suited to returning values in many cases if you plan on having a specific
return value if an exception(s) is/are raised. Finally clauses lend
themselves quite well to cleanup code, streams, connections and the like,
but return values aren't really well suited to it. Every MCAD test guide
I've seen raises this issue ;-).


"Tom Leylan" <gee@iamtiredof spam.com> wrote in message
news:%23l%237tq t6DHA.2952@TK2M SFTNGP09.phx.gb l...[color=blue]
> Turns out it wasn't such a good call. I swear I tested the code but
> "something" mixed me up.
>
> The Return statement is deferred until after the finally statement
> executes... the line is executed but it doesn't actually exit at that[/color]
point.[color=blue]
> So anyway, it would work but I posted slightly different syntax (using the
> function name) which makes it clearer (to me) that it is only assigning[/color]
the[color=blue]
> value and can't possibly return at that point.
>
> Tom
>
>
> "William Ryan eMVP" <bill@NoSp4m.de vbuzz.com> wrote in message
> news:O3tDues6DH A.1816@TK2MSFTN GP12.phx.gbl...[color=green]
> > Tom:
> >
> > Good call, and yes you're absolutely correct. I realize my answer may[/color]
> have[color=green]
> > been misleading -- I was answering it in the context of if an exception[/color]
> was[color=green]
> > caused b/c it seemed he was asking about the behavior of Finally.[/color]
> However,[color=green]
> > if you don't return a value in this instance, it will in fact return[/color]
> false.[color=green]
> > That's more a function of how VB.NET can allow you to not explicitly[/color]
> return[color=green]
> > a value in a function but you have a good point nonetheless.
> >
> > I'll be more clear next time.
> >
> > bill
> > "Tom Leylan" <gee@iamtiredof spam.com> wrote in message
> > news:eOf9qQs6DH A.1936@TK2MSFTN GP12.phx.gbl...[color=darkred]
> > > William... I believe we need to clarify something. It isn't going to
> > > return FALSE because of the way he wrote it. It is going to return[/color][/color]
> FALSE[color=green][color=darkred]
> > > because it ends up FALSE when no return value has been set.
> > >
> > >
> > > Woody... I don't think you want it to just "accidental ly" work. Test[/color][/color][/color]
it[color=blue][color=green][color=darkred]
> > > yourself but (as part of the test) have a function return an integer[/color][/color][/color]
so[color=blue][color=green]
> > you[color=darkred]
> > > can get more than 2 return values.
> > >
> > > Unless I'm greatly mistaken it works as follows:
> > >
> > > You want two return statements in your code: Return True in the Try[/color][/color]
> block[color=green][color=darkred]
> > > and Return False after the End Try. With no return in Catch or[/color][/color][/color]
Finally.[color=blue][color=green][color=darkred]
> > >
> > > If there is no error it will return the value in the Try block (TRUE)[/color][/color][/color]
if[color=blue][color=green][color=darkred]
> > > there is an error the Catch block executes, the the Finally and you[/color][/color][/color]
will[color=blue][color=green][color=darkred]
> > > return the value of the Return statement (FALSE).
> > >
> > > Interestingly even if you place a return statement in the Catch block[/color][/color][/color]
it[color=blue][color=green][color=darkred]
> > > will not be returned. Either the Try return works or the final return[/color]
> > does.[color=darkred]
> > >
> > > Test it out...
> > > Tom
> > >
> > >
> > >
> > > "William Ryan eMVP" <bill@NoSp4m.de vbuzz.com> wrote in message
> > > news:uFrMFxr6DH A.2952@TK2MSFTN GP09.phx.gbl...
> > > > Finally will always be executed and yes, it will still return false[/color][/color]
> the[color=green][color=darkred]
> > > way
> > > > you wrote it.
> > > > "Woody Splawn" <woody@splawns. com> wrote in message
> > > > news:u7eMoqr6DH A.2300@TK2MSFTN GP10.phx.gbl...
> > > > > I have a try catch statement in a fucntion that is supposed to[/color][/color]
> return[color=green]
> > a[color=darkred]
> > > > true
> > > > > or a false
> > > > >
> > > > > My code looks like this:
> > > > >
> > > > > Try
> > > > > mySqlConnection .Open()
> > > > > Dim Da1 As New SqlDataAdapter( "Select JnlType,[/color][/color]
> Description[color=green][color=darkred]
> > > > from
> > > > > JnlType", mySqlConnection )
> > > > > Dim Ds As New DataSet("X")
> > > > > Da1.Fill(Ds)
> > > > > Catch
> > > > > MsgBox("There was a problem filling the Dataset for[/color][/color]
> Lookup[color=green][color=darkred]
> > > > table
> > > > > for JnlType")
> > > > > Return False
> > > > > Finally
> > > > > If mySqlConnection .State = ConnectionState .Open Then
> > > > > mySqlConnection .Close()
> > > > > End If
> > > > > End Try
> > > > >
> > > > > My question is this: Is the Try Catch code smart enough to run[/color][/color][/color]
the[color=blue][color=green][color=darkred]
> > > > Finally
> > > > > statment after the MsgBox and then return false or do I need to[/color][/color]
> write[color=green][color=darkred]
> > > the
> > > > > code some other way. This is what I want it to do but I am not[/color][/color][/color]
sure[color=blue]
> I[color=green][color=darkred]
> > > > have
> > > > > it written correctly.
> > > > >
> > > > >
> > > > >
> > > >
> > > >
> > >
> > >[/color]
> >
> >[/color]
>
>[/color]

[Peter Huang]

RE: Try Catch question

Hi Woody,

Thanks for posting in the community.

First of all, I would like to confirm my understanding of your issue.
From your description, I understand that you are confused by the
Try...Catch...F inally...End Try Block.
Have I fully understood you? If there is anything I misunderstood, please
feel free to let me know.

I think in the Try...Catch...F inally...End Try statement, if there is
Exceptionin the Try and The Exception was catched by Catch statement, the
Catch statement will be run.
And the Finally block will be called whether there is Exception in the Try
or not.

Here is my demo code you may run it to see if this will help you to
understand the Structured Exception Handling.
Module Module3
Public Function Func(ByVal isEx As Boolean) As Boolean
Try
Console.WriteLi ne("Try Block")
If isEx Then
Throw New Exception("Thro w Error")
End If
Return True
Catch ex As Exception
Console.WriteLi ne("Catch Block:" + ex.Message)
Return False
Finally
Console.WriteLi ne("Finally Block")
End Try
Console.WriteLi ne("This line of code will not be run")
End Function
Public Sub Main()
Console.WriteLi ne(Func(True))
Console.WriteLi ne()
Console.WriteLi ne(Func(False))
End Sub
End Module

Also you may take a look at the link below,
Walkthrough: Structured Exception Handling

http://msdn.microsoft.com/library/default.asp?url=/library/en-us/vbcn7/html/

vawlkWalkthroug hStructuredExce ptionHandling.a sp


Best regards,

Peter Huang
Microsoft Online Partner Support

Get Secure! - www.microsoft.com/security
This posting is provided "AS IS" with no warranties, and confers no rights.

[Cor]

Re: Try Catch question

Hi Woody, Tom, Bill

I do it totaly different from the rest and I think this is the best way (for
a dataadapter)

:-))

\\\
Try
Dim Da1 As New SqlDataAdapter _
("Select JnlType, Description from JnlType",
mySqlConnection )
Dim Ds As New DataSet("X")
Da1.Fill(Ds)
Catch sqlExc As SqlException
MessageBox.Show (sqlExc.ToStrin g)
Return False
Catch ex As Exception
MessageBox.Show (ex.Message)
Return False
Finally
mySqlConnection .Close()
End Try
Return True ' Tom, I would have forgotten this if I had not looked at your
message.
///

[Cor]

Re: Try Catch question

Hi

A correction Jon pointed me on.

And than it becomes in my opinon.
\\\with a single datatable to fill
Try
Dim Da1 As New SqlDataAdapter _
("Select JnlType, Description from JnlType",
mySqlConnection )
Dim Ds As New DataSet("X")
Da1.Fill(Ds)
Catch sqlExc As SqlException
MessageBox.Show (sqlExc.ToStrin g)
Return False
Catch ex As Exception
MessageBox.Show (ex.Message)
Return False
End Try
Return true
///
Or with a multiple datatable to fill
\\\
Try
mySQLConnection .open
Try
Dim Da1 As New SqlDataAdapter _
("Select JnlType, Description from JnlType",
mySqlConnection )
Dim Ds As New DataSet("X")
Da1.Fill(Ds,"Ta ble1")
dim da.command = ("Select JnlType, Description from
JnlType2")
Da1.Fill(Ds,"Ta ble2")
Catch sqlExc As SqlException
MessageBox.Show (sqlExc.ToStrin g)
Return False
Catch ex As Exception
MessageBox.Show (ex.Message)
Return False
End Try
Catch ex As Exception
MessageBox.Show (ex.Message)
Return False
Finally
mySQLConnection .close
End Try
Return true
///