[excel] Get values from a listbox on a sheet

I have a listbox named ListBox1 on Sheet1 of an Excel workbook.

Every time the user selects one of the items in the list, I need to copy its name to a variable named strLB.

So, if I have Value1, Value2, Value3, Value4 and the user selects Value1 and Value3, I need my strLB to come out as Value1,Value3.

I tried doing that post hoc with:

For i = 1 To ActiveSheet.ListBoxes("ListBox1").ListCount
    If ActiveSheet.ListBoxes("ListBox1").Selected(i) Then strLB = strLB & etc.etc.
Next i

But this is very slow (I have 15k values in my listbox). This is why I need to record the selection in real time and not in a cycle, after the user is done inputting.

I'm going to also need a way to check if the user removed any of the previous selection.

Take selected value:

worksheet name = ordls
form control list box name = DEPDB1

selectvalue = ordls.Shapes("DEPDB1").ControlFormat.List(ordls.Shapes("DEPDB1").ControlFormat.Value)

The accepted answer doesn't cut it because if a user de-selects a row the list is not updated accordingly.

Here is what I suggest instead:

Private Sub CommandButton2_Click()
    Dim lItem As Long

    For lItem = 0 To ListBox1.ListCount - 1
        If ListBox1.Selected(lItem) = True Then
            MsgBox(ListBox1.List(lItem))
        End If
    Next
End Sub

Courtesy of http://www.ozgrid.com/VBA/multi-select-listbox.htm

To get the value of the selected item of a listbox then use the following.

For Single Column ListBox: ListBox1.List(ListBox1.ListIndex)

For Multi Column ListBox: ListBox1.Column(column_number, ListBox1.ListIndex)

This avoids looping and is extremely more efficient.