CODEWITHSUNDEEP
vb.netoop
James
James

Reputation: 31

Error when creating instance of a class

I'm trying to assign an arrayList a instance of a class but it is giving me the following error.

Object reference not set to an instance of an object.

This is my code that assigns it.

Public memberList As ArrayList

Public Sub LoadUser()
Dim userId As Integer = 0
    Dim userData As Data.DataTable = oExecuteSimpleQuery_DT("QA", "SELECT * FROM Member")
    If userData IsNot Nothing Then
        For Each user As Data.DataRow In userData.Rows
            If memberList(userId) Is Nothing Then
                memberList(userId) = 1
            End If
            memberList(userId) = New clsMember(user("UserID"), user("Firstname"), user("Secondname"), user("Username"), user("Password"), user("Email"), user("Rights"))
            userId += 1
        Next
    End If
End Sub

Upvotes: 0

Views: 78

Answers (2)

Markus
Markus

Reputation: 22511

In the code shown in your question you do declare the memberList variable, but you do not create an instance. In order to solve the error, change the first line to: 

Public memberList As New ArrayList()

Two side nodes:

  • Instead of using ArrayList, have a look at List(Of T). It offers almost the same functionality, but is strongly typed.
  • A NullReferenceException is a common error that is worth understanding. See this link for details on the reasons and on how to fix them.

Upvotes: 3

Ranhot
Ranhot

Reputation: 334

try this:

Public memberList as New List(Of clsMember)


Public Sub LoadUser()
 Dim userId As Integer = 1
 Dim userData As Data.DataTable = oExecuteSimpleQuery_DT("QA", "SELECT * FROM Member")
 If userData IsNot Nothing Then
    For Each user As Data.DataRow In userData.Rows
        memberList.Add(New clsMember(user("UserID"), user("Firstname"), user("Secondname"), user("Username"), user("Password"), user("Email"), user("Rights"))
        userId += 1
    Next
 End If
End Sub

Upvotes: 1

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