Cannot initialize array

[wsyeager]

I'm wondering if somebody could help me resolve the infamous ""Object reference not set to an instance of an object." when I try to execute the following:

 

I have a class like the following:

Partial Public Class BinaryTreeSrchCrit

   Private intFldNum As Integer
   Private strSrchValue As String
   Private strOperator As String
   Private intSrchID As Integer
   Private intGrpIdx As Integer
   Private intPropIdx1 As Integer
   Private intPropIdx2 As Integer
   Private strLogicalOperator As String
   Private intRelIdx As Integer
   Private blnTrVal As Boolean
   Private strLRNode As String
   Private tnUlink As BinaryTreeSrchCrit 'top node of the tree
   Private tnLlink As BinaryTreeSrchCrit 'left node of the tree
   Private tnRlink As BinaryTreeSrchCrit 'right node of the tree

   Public Property FldNum() As Integer
       Get
           Return intFldNum
       End Get
       Set(ByVal Value As Integer)
           intFldNum = Value
       End Set
   End Property

   Public Property SrchValue() As String
       Get
           Return strSrchValue
       End Get
       Set(ByVal Value As String)
           strSrchValue = Value
       End Set
   End Property
.
.
.

 

In my app, I have the following code to try and populate the class:

Dim btSrchCrit(tblSrchCrit.Rows.Count - 1) As BinaryTreeSrchCrit
               For i = 0 To tblSrchCrit.Rows.Count - 1
                   If Not tblSrchCrit.Item(i).IsFldNumNull Then
                       btSrchCrit(i).FldNum = tblSrchCrit.Item(i).FldNum
                   End If
                   If Not tblSrchCrit.Item(i).IsGrpIdxNull Then
                       btSrchCrit(i).GrpIdx = tblSrchCrit.Item(i).GrpIdx
                   End If
                   If Not tblSrchCrit.Item(i).IsLogicalOperatorNull Then
                       btSrchCrit(i).LogicalOperator = tblSrchCrit.Item(i).LogicalOperator
                   End If
                   If Not tblSrchCrit.Item(i).IsPropIdx1Null Then
                       btSrchCrit(i).PropIdx1 = tblSrchCrit.Item(i).PropIdx1
                   End If
                   If Not tblSrchCrit.Item(i).IsPropIdx2Null Then
                       btSrchCrit(i).PropIdx2 = tblSrchCrit.Item(i).PropIdx2
                   End If
                   btSrchCrit(i).RelIdx = tblSrchCrit.Item(i).RelIdx
                   btSrchCrit(i).SrchID = tblSrchCrit.Item(i).SrchID
                   If Not tblSrchCrit.Item(i).IsSrchValueNull Then
                       btSrchCrit(i).SrchValue = tblSrchCrit.Item(i).SrchValue
                   End If
                   If Not tblSrchCrit.Item(i).Is_OperatorNull Then
                       btSrchCrit(i)._Operator = tblSrchCrit.Item(i)._Operator
                   End If
               Next

 

It's giving me the error on the above line:

btSrchCrit(i).FldNum = tblSrchCrit.Item(i).FldNum

 

The following is from my debugging session:

btSrchCrit	{Length=1}	clsParseCDR.BinaryTreeSrchCrit()
	(0)	Nothing	clsParseCDR.BinaryTreeSrchCrit
	btSrchCrit(i)	Nothing	clsParseCDR.BinaryTreeSrchCrit
	i	0	Short

As you can see, there is 1 btSrchCrit object created (since all I have in this case is one record coming into my function).

The 0th index is Nothing. This is why the error is happening, but I don't know how to resolve it. There is a value in "tblSrchCrit.Item(i).FldNum" before it tries to assign it to the property in the array.

After creating an index (Dim btSrchCrit(tblSrchCrit.Rows.Count - 1) As BinaryTreeSrchCrit), I thought that the 0th entry in the array would not be Nothing. You can't create arrays with a "New" keyword.

 

Can somebody please tell me how I can resolve this issue?

 

Thanks so much....

Edited April 19, 2006 by PlausiblyDamp

[PlausiblyDamp]

When you create an array of reference types (classes) you do not get the elements themselves created - every element is nothing until you store something in it.