Self-Referential Classes

A self-referential class contains an instance variable that refers to another object of the same class type. For example, the declaration

 class Node
 {
 private int data;
 private Node nextNode; // reference to next linked node

 public Node( int data ) { /* constructor body */ }
 public void setData( int data ) { /* method body */ }
 public int getData() { /* method body */ }
 public void setNext( Node next ) { /* method body */ }
 public Node getNext() { /* method body */ }
 } // end class Node

declares class Node, which has two private instance variablesinteger data and Node reference nextNode. Field nextNode references a Node object, an object of the same class being declared herehence, the term "self-referential class." Field nextNode is a linkit "links" an object of type Node to another object of the same type. Type Node also has five methods: a constructor that receives an Integer to initialize data, a setData method to set the value of data, a getdata method to return the value of data, a setNext method to set the value of nextNode and a getNext method to return a reference to the next node.

Programs can link self-referential objects together to form such useful data structures as lists, queues, stacks and trees. Figure 17.1 illustrates two self-referential objects linked together to form a list. A backslashrepresenting a null referenceis placed in the link member of the second self-referential object to indicate that the link does not refer to another object. Note the backslash is illustrative; it does not correspond to the backslash character in Java. Normally, a null reference indicates the end of a data structure. There are other ways to represent the end of a data structure that are beyond the scope of this text.

Figure 17.1. Self-referential-class objects linked together.


Introduction to Computers, the Internet and the World Wide Web

Introduction to Java Applications

Introduction to Classes and Objects

Control Statements: Part I

Control Statements: Part 2

Methods: A Deeper Look

Arrays

Classes and Objects: A Deeper Look

Object-Oriented Programming: Inheritance

Object-Oriented Programming: Polymorphism

GUI Components: Part 1

Graphics and Java 2D™

Exception Handling

Files and Streams

Recursion

Searching and Sorting

Data Structures

Generics

Collections

Introduction to Java Applets

Multimedia: Applets and Applications

GUI Components: Part 2

Multithreading

Networking

Accessing Databases with JDBC

Servlets

JavaServer Pages (JSP)

Formatted Output

Strings, Characters and Regular Expressions

Appendix A. Operator Precedence Chart

Appendix B. ASCII Character Set

Appendix C. Keywords and Reserved Words

Appendix D. Primitive Types

Appendix E. (On CD) Number Systems

Appendix F. (On CD) Unicode®

Appendix G. Using the Java API Documentation

Appendix H. (On CD) Creating Documentation with javadoc

Appendix I. (On CD) Bit Manipulation

Appendix J. (On CD) ATM Case Study Code

Appendix K. (On CD) Labeled break and continue Statements

Appendix L. (On CD) UML 2: Additional Diagram Types

Appendix M. (On CD) Design Patterns

Appendix N. Using the Debugger

Inside Back Cover



Java(c) How to Program
Java How to Program (6th Edition) (How to Program (Deitel))
ISBN: 0131483986
EAN: 2147483647
Year: 2003
Pages: 615

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