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Null reference exception warning

Posted on 2007-03-30
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Last Modified: 2013-11-26
I have following code in VB.NEt 2005:

Dim objCardDetails As frmtCardDetails

Try
        'I have some 20 lines of code here and then the below code
                intAccountNr = GetAccountNr()
            objCardDetails = New frmtCardDetails(intAccountNr )
Catch
Finally
End Try

Now I get following warning:
Warning      9      Variable 'objCardDetails' is used before it has been assigned a value. A null reference exception could result at runtime.

How should I initialize this variable?

Regards
MI
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Comment
Question by:vj_mi
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6 Comments
 
LVL 142

Accepted Solution

by:
Guy Hengel [angelIII / a3] earned 250 total points
ID: 18824664
do you use the variable objCardDetails somewhere above that line? I guess so, because otherwise that warning should not be issued
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LVL 85

Expert Comment

by:Mike Tomlinson
ID: 18824735
I agree.

Show us the 20 lines:

    "I have some 20 lines of code here and then the below code"

or more of your code...
0
 

Author Comment

by:vj_mi
ID: 18824787
No I have not used that variable. I have similar issue at most of the places. I declare a variable of type form and I use it somewhere down belowI get this error.

The earlier code is somthing like this:
        If c.Style Is Nothing Then
            If mViewStyle Is Nothing Then
                mViewStyle = grdTemp.Styles.Add(c.FieldName, "")
                mViewStyle.Options = StyleOptions.UseHorzAlignment
            End If
            c.StyleName = mViewStyle.StyleName
        End If
        c.Style.HAlignment = HorzAlignment.Near

Regards,
MI
0
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LVL 142

Expert Comment

by:Guy Hengel [angelIII / a3]
ID: 18824925
do you have that line:
objCardDetails = New frmtCardDetails(intAccountNr )
inside an if / else statement?

0
 

Author Comment

by:vj_mi
ID: 18828924
No... it is not inside the If statement.

What will happen if I initialize to Nothing, like:

Dim objCardDetails As frmtCardDetails = nothing

Regards,
MI
0
 
LVL 85

Assisted Solution

by:Mike Tomlinson
Mike Tomlinson earned 250 total points
ID: 18829153
It can't hurt.

...but still shouldn't make a difference given the code you've posted thus far.
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Our Dev teams are like yours. They’re continually cranking out code for new features/bugs fixes, testing, deploying, testing some more, responding to production monitoring events and more. It’s complex. So, we thought you’d like to see what’s working for us.

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