Structure in Arraylist in Structure

M

martialarts

Regular
Joined
Jun 20, 2003
Messages
59
Location
Chicago Area
I am trying to create a structure that contains an arraylist of another structure. As far as I know an arraylist can be a member of a structure and an arraylist can contain any object, including another structure... so I don't know what the problem is. The compiler is stopping on

Code: 
results.elementArray.Add(elementInfo)

and saying:
"An unhandled exception of type 'System.NullReferenceException' occurred in application.exe

Additional information: Object reference not set to an instance of an object."

I think it is upset about elementArray. Can anyone offer any advice? Here is the code:

Code: 
Module ModuleParse
    Structure elementStruct
        Public name As String
        Public clinicalLow As Decimal
        Public clinicalHigh As Decimal
        Public value As String
    End Structure

    Structure resultsStruct
        Public patientID As String
        Public lastName As String
        Public firstName As String
        Public gender As String
        Public birthdate As String
        Public weight As String
        Public bloodType As String
        Public dateDrawn As String
        Public elementArray As ArrayList
    End Structure

    Function parseResults(ByRef results As resultsStruct)
        Dim elementInfo As elementStruct
        results.patientID = "123456"

        elementInfo.name = "Nitrogen"
        elementInfo.clinicalLow = 44
        elementInfo.clinicalHigh = 51.7

        results.elementArray.Add(elementInfo)

        Return results
    End Function
End Module

Thanks!
 
Got it

I found my problem. I was missing this:
Code: 
results.elementArray = New ArrayList
I added it after setting results.patientID and this fixed it.
 
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