I have attached an example which invokes a method in a class that will create a List object containing the records of a data file and then return that list to the form so that it can be used in binding to a combobox control.
The source is as follows:
class-id bindcombo.Form1 is partial
inherits type System.Windows.Forms.Form.
working-storage section.
method-id NEW.
procedure division.
invoke self::InitializeComponent
declare fl as type bindcombo.fillList = new bindcombo.fillList
set bindingSource1::DataSource to fl::getList
set comboBox1::DataSource to bindingSource1::DataSource
goback.
end method.
method-id button1_Click final private.
procedure division using by value sender as object e as type System.EventArgs.
invoke self::Close
end method.
method-id comboBox1_SelectionChangeCommitted final private.
procedure division using by value sender as object e as type System.EventArgs.
invoke type MessageBox::Show("Selection is " & comboBox1::SelectedItem)
end method.
end class.
class-id bindcombo.fillList.
select item-file assign to "itemfile.txt"
organization is line sequential
file status is file-status.
file section.
fd item-file.
01 item-record pic x(10).
working-storage section.
01 file-status pic x(2) value spaces.
method-id getList.
local-storage section.
procedure division returning mylist as list[string].
open input item-file
create mylist
perform until exit
read item-file
at end
exit perform
not at end
write mylist from item-record
end-read
end-perform
close item-file
goback.
end method.
end class.