1. Slides by Steve Armstrong LeTourneau University Longview, TX
Inheritance and Lists
Chapter 14
Slides by Steve Armstrong LeTourneau University Longview, TX
ã 2007, Prentice Hall

2. Chapter Contents Using Inheritance to Implement a Sorted List
Designing a Base Class
Creating an Abstract Base Class
An Efficient Implementation of a Sorted List
The Method add
Carrano, Data Structures and Abstractions with Java, Second Edition, (c) 2007 Pearson Education, Inc. All rights reserved X

3. Using Inheritance to Implement a Sorted List
View revised SortedList class which inherits from LList
Problem
It inherits two methods which, if used could destroy the order of the entries in a sorted list
Carrano, Data Structures and Abstractions with Java, Second Edition, (c) 2007 Pearson Education, Inc. All rights reserved X

4. Using Inheritance to Implement a Sorted List
Possible solutions
Declare sorted list as an instance of SortedListInterface
Implement the add and replace within SortedList, but have them return false
Implement them but have them throw an exception
Carrano, Data Structures and Abstractions with Java, Second Edition, (c) 2007 Pearson Education, Inc. All rights reserved X

5. Designing a Base Class Note excerpt of class LList
We want LList as base class for further development
Efficient extension will require subclass access to
Data field firstNode
Method getNodeAt
Class Node
Carrano, Data Structures and Abstractions with Java, Second Edition, (c) 2007 Pearson Education, Inc. All rights reserved X

6. Designing a Base Class
Fig A derived class of the class LList cannot access or change anything that is private within LList
Carrano, Data Structures and Abstractions with Java, Second Edition, (c) 2007 Pearson Education, Inc. All rights reserved X

7. Protected Access
You can access a protected method or data field of a given class by name only …
Within its own class definition
Within a class derived from that class
Within any class in the same package as that class
Carrano, Data Structures and Abstractions with Java, Second Edition, (c) 2007 Pearson Education, Inc. All rights reserved X

8. Changes to LList Declare firstNode and length to be protected
Provide protected methods
addFirstNode
addAfterNode
removeFirstNode
removeAfterNode
Make getNodeAt protected
Carrano, Data Structures and Abstractions with Java, Second Edition, (c) 2007 Pearson Education, Inc. All rights reserved X

9. Changes to LList Make class Node and its constructors protected
Add protected methods
setData
getData
setNextNode
getNextNode
View code samples of changes
Carrano, Data Structures and Abstractions with Java, Second Edition, (c) 2007 Pearson Education, Inc. All rights reserved X

10. Designing a Base Class
Fig Access available to a class derived from the class LinkedListRevised
Carrano, Data Structures and Abstractions with Java, Second Edition, (c) 2007 Pearson Education, Inc. All rights reserved X

11. Creating an Abstract Base Class
Simplify class LListRevised
Note portion that deals with chain of linked nodes
Place that portion into an abstract base class
View code for LinkedChainBase
Note next iteration of LListRevised which extends LinkedChainBase
Carrano, Data Structures and Abstractions with Java, Second Edition, (c) 2007 Pearson Education, Inc. All rights reserved X

12. Efficient Implementation of a Sorted List
The class LinkedListBase enables faster manipulation of the list's underlying data structure
We want the class to extend LinkedChainBase
public class SortedLinkedList < T extends Comparable < ? super T >> extends LinkedChainBase < T > implements SortedListInterface < T > , java.io.Serializable
Carrano, Data Structures and Abstractions with Java, Second Edition, (c) 2007 Pearson Education, Inc. All rights reserved X

13. New and Revised Methods
Note revised add method
Note differences from add method in Segment 13.10
Proceeding protected methods with super is optional
No other methods have their methods
View private method getNodeBefore
Carrano, Data Structures and Abstractions with Java, Second Edition, (c) 2007 Pearson Education, Inc. All rights reserved X

14. Efficiency getPosition is O(n2) Improved add method is O(n)
The class designer should use inheritance and maintain efficiency
Requires that base class provided protected access to underlying data structure
Carrano, Data Structures and Abstractions with Java, Second Edition, (c) 2007 Pearson Education, Inc. All rights reserved X