PartiallyImperative.java

// Somewhere on the road from imperative to functional...
public class PartiallyImperative {
    // @Inject
    private ItemRepository itemRepository;
    // @Inject
    private InventoryLocationRepostitory;

    // Optionally return inventory location with available inventory for item with the given id
    public Optional<InventoryLocation> itemByFirstAvailable(String itemId) throws NotFoundException {

        // Find the item by id optionally - the type safe way of encoding null values.
        Optional<Item> itemOptional = itemRepository.findByItemId(itemId);

        // Unwrap the Item from the Optional or throw not found if the item doesn't exist
        Item item = itemOptional.orElseThrow(() -> new NotFoundException("itemId cannot be null"));

        // Get all known inventory locations for the item
        List<InventoryLocation> inventoryLocations = inventoryLocationRepostitory.findByItemId(item);

        // Optionally return the first inventory location with non-zero inventory
        return inventoryLocations.stream()
                .filter(inventoryLocation -> inventoryLocation.getInStock() > 0).findFirst();
    } 
}
// Half the line numbers of the fully imperative version
// What in here is NOT cruft? 
// No null checks!!