I think that you're confusing the STATE of the ULV (the used layouts, the current position, the selected items, etc.) with the CONTENTS of the ULV, which is kept in a separate data container (I suppose that you store all displayed data in a list, an array, a map, etc., so your question is probably to know how to save this memory content to the disk; in this case, read this tutorial). The ULV cannot save something that is external to it (it has no idea of how you store and retrieve your data).