XL2000: How to Programmatically Create a Collection

Programming functionality in Microsoft Excel allows you to create a collection. A collection is a predefined object that stores groups of related objects, making it easier to work with the object group. For example, you can use a For Each loop statement to loop through the collection. Each time the macro executes the loop, it references a different object in the collection until all objects in the collection are referenced once.

This article includes a sample Visual Basic for Applications macro that creates and references a collection.

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To create the collection, declare an object as a new collection. After you create the Collection object, you may add items to the collection using the Add method or remove items using the Remove method.

To create a collection, follow these steps:

1. Open a new workbook, and then start the Visual Basic Editor (press ALT+F11).
2. On the Insert menu, click Class Module.
3. In the class module, type the following declaration:

   Public EmployeeName As String
   						

   You typically use a public variable in a class module to define properties for the class.
4. If the Properties window is not visible, click Properties Window on the View menu.
5. If the Project Explorer window is not visible, click Project Explorer on the View menu.
6. In the Project Explorer window, click the class module you inserted in step 2.
7. In the Properties window, change the (Name) property of the class module to EmpClass.
8. On the Insert menu, click Module.
9. In this module, type the following code:

   Sub MyCollection()
   
      Dim employees As New Collection   'Create the collection object.
      Dim num As Integer
   
      num = 0    'Counter for number of employees added to the
                   'collection.
   
      Do
      Dim employee As New EmpClass    'Create new instance of the
                                            'EmpClass class.
      num = num + 1
   
      newname = InputBox("Enter new employee name" & Chr(13) _
             & "or press Cancel to see list of employees.")
   
      If newname <> "" Then   'You did not press Cancel.
   
             employee.EmployeeName = newname
             employees.Add Item:=employee, key:=CStr(num)
   
             Set employee = Nothing    'Clear the current reference
                                          'in preparation for next one.
   
      End If
   
      Loop Until newname = ""  'You pressed Cancel.
   
      For Each x In employees
         MsgBox x.EmployeeName 'Display the employee name.
      Next
   
      MsgBox employees.Count  'Current number of employees in collection.
   
      For Each x In employees
          employees.Remove 1   'Remove each employee from the collection.
   
      Next
   
      MsgBox employees.Count 'Display a count of zero because
                               'all employees were removed from the
                               'collection.
   
   End Sub
   					

10. Run the MyCollection macro.
11. When you are prompted, type any names and click OK after each name. Click Cancel to stop typing names.

Message boxes that display each of the names you typed appear, and then a message box that displays a count of the names you typed appears. Another message box with a count of zero appears because the last For Each loop statement removes each employee from the collection.

For more information about the Add method, in the Visual Basic Editor, click Microsoft Visual Basic Help on the Help menu, type add method in the Office Assistant or the Answer Wizard, and then click Search to view the topic.

For more information about collections, in the Visual Basic Editor, click Microsoft Visual Basic Help on the Help menu, type collection object in the Office Assistant or the Answer Wizard, and then click Search to view the topic.