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How do I initialize/utilize an arraylist and a hashtable defined in a different class?

Posted on 2008-06-26
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Last Modified: 2010-07-27
Friends,

I have a routine where I need to clear 2 arrays and a hashtable, but they are defined in a different class (frmTimelineViewer).  

I tried doing a Dim aFFOrder as New... But it isn't available from the list of options when I type frmTimelineViewer.

How do I intialize/utilize these arraylists and the hashtable from another class?

Regards,
Eric
Public Sub ProcessFFData(ByVal Lap As Integer, ByVal RunID As Integer)
        frmTimelineSerial.lvFF.Clear()
        frmTimelineSerial.lvFF.Columns.Add("No")
        frmTimelineSerial.FFOrderArray.Clear() 'If I try to run this or any of the following 2 lines, I get a NullReferenceException Error. 
        frmTimelineSerial.FFOrderDoNotIncludeHT.Clear()
        frmTimelineSerial.FFOrderHT.Clear()
 
        Using TableAdapter As New ReportingDataTableAdapters.FFOrderTableAdapter()
            Using DataTable As ReportingData.FFOrderDataTable = TableAdapter.GetData(Lap, RunID)
                Dim Row As ReportingData.FFOrderRow
                Dim li As ListViewItem
                Dim i As Integer = 0
                For Each Row In DataTable
                    li = frmTimelineSerial.lvFF.Items.Add(Row.CarNumber)
                    frmTimelineSerial.FFOrderArray.Add(Row.CarNumber) ' The same thing happens with these two lines.
                    frmTimelineSerial.FFOrderHT.Add(Row.CarNumber, i)
                Next
            End Using
        End Using
    End Sub

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Question by:indy500fan
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4 Comments
 
LVL 86

Accepted Solution

by:
Mike Tomlinson earned 2000 total points
ID: 21877405
Either...

(1) Pass a reference to those objects into your sub.
(2) Make them shared so you can access them from anywhere.
(3) Place them in a Module as Public so they can be accessed from anywhere.

There are other methods depending on your situation...
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Author Comment

by:indy500fan
ID: 21877449
Would you agree declaring them as the following would be wrong?  Should I declare them as New or is that a bad idea?

   Public Shared FFOrderArray As New ArrayList

    Public Shared FFNewOrderArray As New ArrayList

    Public Shared FFOrderDoNotIncludeInOrderArray As New ArrayList

    Public Shared FFOrderHT As New Hashtable

    Public Shared FFOrderDoNotIncludeHT As New Hashtable
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Author Comment

by:indy500fan
ID: 21877491
Duh, I just need the new clause.  I had brainfade and wasn't thinkin clearly.

Thanks for your help!
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LVL 86

Expert Comment

by:Mike Tomlinson
ID: 21877504
"Wrong" is really only relative to YOUR situation.

If those items only ever need ONE instance of them across all forms then it's fine.

You could then access them with:

    frmTimelineViewer.FFOrderArray

etc...

If you need a seperate copy of each one for every instance of the form then this is not a viable approach.
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