One of the concrete classes that implements Collection is java.util.LinkedList. This class is just a plain old “Data Structures 101” forward-and-backward-linked list. You provide separate objects that you want stored, and the library class does the work of setting up and copying references to make a list. You start by instantiating an empty LinkedList, then anything you add is put on the list as a new element.
The class LinkedList implements List which implements Collection. The exact parent-child relationship of interfaces is shown in Figure 16-1.
Figure 16-1. Interface relationship
The interface java.util.List ...