loading and passing combobox

Hey all. I'm having problems determining how to do this.
I have a class that loads 42000+ items into a combobox that is used on multiple forms. I want to load this combobox during the time that the splash-screen is showing, and then just reference it from other forms.

My class code looks something like this:

Code:

---

    Public Shared Function LoadZipCodes(ByRef cmbCombo As ComboBox)
        Dim cmbZip As ComboBox
        GenericCode(1, "Zip Code", cmbZip)
        cmbCombo = cmbZip
        Return cmbCombo
    End Function

---

I know that it populates the combobox, and I'm pretty sure to put the call to that function in the splashscreen_load sub. What is the best way to pass it to another form, or should I make a global variable that can be used project-wide and just have my comboboxes ref that for the data? I want to try to eliminate processing time as much as possible between switching forms.

Your help is much appreciated.

I would do it as a global, since it is going to be accessed throughout the application.

Ok, sorry to bother again, but I'm getting the error of:
"Object reference not set to an instance of an object"
when I do this. Also where should my call to the function to load the combo box be if I want it to run only once and run while the user can see the SplashScreen form?

here is my code:

Module

Code:

---

Public cmbZips As ComboBox
public sub Main()....

---

Splash Screen

Code:

---

  Private Sub loadZipCodes()
        Dim clsPrac As clsPractice
        clsPrac.GenericCode(1, "Zip Code", cmbZips)
    End Sub

---

clsPractice

Code:

---

  Public Shared Sub GenericCode(ByVal intProcess As Integer, ByVal strProcess As String, ByRef cmbBox As ComboBox)
        'intProcess 1 = Load Zip Code
        'intProcess 2 = Load States
        Dim objAdapter As OleDb.OleDbDataAdapter
        Dim objTable As New DataTable
        Dim objItem As ListItemNumeric
        Dim strSQL As String
        Dim strConn As String
        Dim intLoop, records As Integer
        Dim str1, str2, str3 As String

        Select Case intProcess
            Case 1 ' load zip codes
                strSQL = "Select * from Zip, State where Zip.State = StateAbb"
                str1 = "num"
                str2 = "Zip"
            Case 2 ' load states
                strSQL = "Select StateID, StateAbb, StateName From State"
                str1 = "StateID"
                str2 = "StateName"
            Case 3 'load tech
                strSQL = "Select * from Tech, Inventory, Company where inv_tech_num = tech_num and tech_comp_num = company_num"
                str1 = "Tech.num"
                str2 = "tech_num"
            Case Else
                MessageBox.Show("There is some kind of error", "ERROR")
        End Select

        strConn = ConnectStringBuild()

        Try
            objAdapter = New OleDb.OleDbDataAdapter(strSQL, strConn)
            objAdapter.Fill(objTable)
            records = objTable.Rows.Count - 1
            If records > 43000 Then records = 9
            For intLoop = 0 To records
                objItem = New ListItemNumeric
                With objTable.Rows(intLoop)
                    objItem.ItemID = CInt(.Item(str1))
                    objItem.ItemValue = .Item(str2).ToString()
                    If intProcess = 1 Then
                        objItem.City = .Item("City").ToString()
                        objItem.State = .Item("StateName").ToString()
                    ElseIf intProcess = 3 Then
                        objItem.TechCompNum = .Item                        objItem.Email = .Item("tech_email").ToString
                    End If
                End With
                cmbBox.Items.Add(objItem)
            Next

            Dim x As Integer
            x = CInt(objTable.Rows(1).Item(str1))

        Catch objException As Exception
            MessageBox.Show(objException.Message, strProcess)
        End Try
    End Sub

---

once again, your help is appreciated. and I'm unsure of how to instantiate the comboBox so I avoid getting that error. Thanks.

declare it as Public Shared

and u can reference it easily from other forms

VB Code:

Public Class Practice
 
    Public Enum LoadType
        ZipCode
        State
        Tech
    End Enum
 
    'proper syntax to use:
    'Practice.GenericCode(LoadType.State, ComboBox1)
    Public Shared Sub GenericCode(ByVal loadTypes As LoadType, ByRef cmbBox As ComboBox)
        Dim objAdapter As OleDb.OleDbDataAdapter
        Dim objTable As New DataTable
        Dim objItem As ListItemNumeric
        Dim strSQL As String
        Dim strConn As String
        Dim intLoop, records As Integer
        Dim str1, str2, str3 As String
 
        Select Case loadTypes
            Case LoadType.ZipCode
                strSQL = "Select * from Zip, State where Zip.State = StateAbb"
                str1 = "num"
                str2 = "Zip"
            Case LoadType.State
                strSQL = "Select StateID, StateAbb, StateName From State"
                str1 = "StateID"
                str2 = "StateName"
            Case LoadType.Tech
                strSQL = "Select * from Tech, Inventory, Company where inv_tech_num = tech_num and tech_comp_num = company_num"
                str1 = "Tech.num"
                str2 = "tech_num"
            Case Else
                MessageBox.Show("There is some kind of error", "ERROR")
        End Select
 
        'Shared methods can't call instance methods so I hope this is another shared method
        strConn = ConnectStringBuild()
 
        Try
            objAdapter = New OleDb.OleDbDataAdapter(strSQL, strConn)
            objAdapter.Fill(objTable)
            records = objTable.Rows.Count - 1
            If records > 43000 Then records = 9
            For intLoop = 0 To records
                objItem = New ListItemNumeric
                With objTable.Rows(intLoop)
                    objItem.ItemID = CInt(.Item(str1))
                    objItem.ItemValue = .Item(str2).ToString()
                    If loadTypes = LoadType.ZipCode Then
                        objItem.City = .Item("City").ToString()
                        objItem.State = .Item("StateName").ToString()
                    ElseIf LoadType.Tech Then
                        objItem.TechCompNum = .Item 'missing fieldname
                        objItem.Email = .Item("tech_email").ToString
                    End If
                End With
                cmbBox.Items.Add(objItem)
            Next
 
            Dim x As Integer = CType(objTable.Rows(1).Item(str1), Integer)
 
        Catch objException As Exception
            MessageBox.Show(objException.Message, loadTypes.ToString)
        End Try
    End Sub
 
End Class