Collection

ArrayList
TreeSet : Keeps the elements sorted and prevents duplicates
HashMap : Let's you store and access elements as name/value pairs
LinkedList : Designed to give better performance when you insert or delete elements from the middle of the collection
HashSet : Prevents duplicates in the collection, and given an element, can find that element in the collection quickly.
LinkedHashMap : Like a regular HashMap, except it can remember the order in which elements(name/value pairs) were inserted, or it can be configured to remember the order in which elements were last accessed

public <T extends Animal> void takeThing(ArrayList<T> list)
  same
public void takeThing(ArrayList<? extends Animal> list)

Related Links
http://java.sun.com/docs/books/tutorial/collections/index.html

References
Head First Java, 2nd Edition. p.533