In Hour 19, “Storing Information in Linked Lists,” you learned how to make a linked list. Your linked list was encapsulated: The list knew only about its head pointer; the head pointer delegated its work to internal pointers, and so forth.
One problem with the linked list was that it only knew how to handle the particular data types it was created to work with. If you wanted to put anything else into your linked list, you couldn’t do it. You couldn’t, for example, make a linked list of
Car objects, or of
Cat objects, or any other object ...