1. Big-Picture & Chapter 5 Why are things so complicated? & Linked Structures

2. Big Picture List (Batters) List (Pitchers) List (Objects) Array-based List List (Batters) List (Pitchers) List (Coaches) Linked-list based … … …

3. Why Interfaces? It defines a standard way that a data structure is used. –Tells you what methods are available –Method name –Parameters –etc. Programmers can switch to a completely different underlying implementation and they only have to change one line of code.

4. Big Picture Listable Batter List (Listable) Array-based List Pitcher Coach Fruitcake Cockroach Linked-list based … … …

5. Why the Listable interface? Wasn’t a list of Objects good enough? Isn’t everything in Java an Object? Yes, but the java.lang.Object does not have methods for comparing Objects Thus, your list can never compare Objects to see if they are in the right order. Thus, you can never have a sorted list.

6. Why the Listable interface? The Listable Interface just provides an abstract method called compare, which can be implemented by any Class. Thus, any Class that implements Listable must implement the compare function. Thus, our List can maintain a sorted list without even knowing any details about the objects stored in the list.

7. Big Picture Player Batter List (Player) Array-based List Pitcher Linked-list based

8. Can we use inheritance? Yes, but here are the problems: List (Players) can only call functions that are implemented in the Player base-class. Players are sorted based on Rating Rating is based on the 10 statistical categories, which are different for batters vs pitchers. Thus, Rating can not be implmented inside of the Player base class.

9. Can we use inheritance? We can create a sorted list of Batters or Pitchers But we can’t put both Batters and Pitchers in a sorted list of Players. Inheritance is really only useful in consolidating fields and methods from a set of classes that are similar. Inheritance does NOT help us create generic data structures.

10. Can we use inheritance? This is why Dr. B thinks that inheritance is not so important Its just a useful way of organizing classes into hierarchies Interfaces are much more useful in terms of recycling code and making generic data structures.

11. Special Classes Self-referential class A class that includes an instance variable or variables that can hold a reference to an object of the same class Inner class A class defined inside of another class. The outer class can access the private variables of the inner class.

12. Chapter 5 Linked Structures

13. StackNode

14. Results of Stack Operations Using StackNode

15. Results of Stack Operations Using StackNode (Cont’d) Internal View Abstract View

16. Results of Stack Operations Using StackNode (Cont’d) Internal View Abstract View

17. Results of Stack Operations Using StackNode (Cont’d) Internal View Abstract View

18. Results of Stack Operations Using StackNode (Cont’d) Internal View Abstract View

20. The push Operation

21. Results of push Operation

22. Results of push Operation (Cont’d)

25. The Code for the push Method

27. The Code for our pop Method

28. The top Method

29. Linked Structures Implementing a Queue

31. A Linked Queue Representation

32. The Enqueue Operation

33. The enqueue Method

34. The Dequeue Operation

35. The dequeue Method

36. Alternate Queue Implementations

37. A Basic Linked List Sorted and Unsorted

38. List with Three Items

40. The isFull and lengthIs Methods

41. The reset and getNextItem Methods

42. getNextItem()

43. The Remaining Methods We define isThere and insert as abstract methods, leaving their implementation to the concrete classes. We implement both retrieve and delete with our abstract LinkedList class.

44. The retrieve Method

46. myList.retrieve(7)

47. Retrieving an Item from a List

48. The delete Method

50. Big-O Comparison of Unsorted List Operations

51. More slides to come… Linked Lists (unsorted first) (then sorted)