Sams Teach Yourself Java 2 in 24 Hours

By Rogers Cadenhead

• Table of Contents
  • Copyright
  • About the Author
  • About the Technical Editor
  • Acknowledgments
  • We Want to Hear from You!
  • Reader Services
  • Introduction
  • Hour 1. Becoming a Programmer
  • Hour 2. Writing Your First Program
  • Hour 3. Vacationing in Java
  • Hour 4. Understanding How Java Programs Work
  • Part II: Learning the Basics of Programming
  • Hour 5. Storing and Changing Information in a Program
  • Hour 6. Using Strings to Communicate
  • Hour 7. Using Conditional Tests to Make Decisions
  • Hour 8. Repeating an Action with Loops
  • Part III: Working with Information in New Ways
  • Hour 9. Storing Information with Arrays
  • Hour 10. Creating Your First Object
  • Hour 11. Describing What Your Object Is Like
  • Hour 12. Making the Most of Existing Objects
    • The Power of Inheritance
    • Establishing Inheritance
    • Working with Existing Objects
    • Workshop: Creating a Subclass
    • Summary
    • Q&A
    • Quiz
    • Activities
  • Part IV: Programming a Graphical User Interface
  • Hour 13. Building a Simple User Interface
  • Hour 14. Laying Out a User Interface
  • Hour 15. Responding to User Input
  • Hour 16. Building a Complex User Interface
  • Part V: Creating Multimedia Programs
  • Hour 17. Creating Interactive Web Programs
  • Hour 18. Handling Errors in a Program
  • Hour 19. Creating a Threaded Program
  • Hour 20. Reading and Writing Files
  • Part VI: Creating Multimedia Programs
  • Hour 21. Using Fonts and Color
  • Hour 22. Playing Sound Files
  • Hour 23. Working with Graphics
  • Hour 24. Creating Animation
  • Part VII: Appendixes
  • Appendix A. Tackling New Features of Java 2 Version 1.4
  • Appendix B. Using the Java 2 Software Development Kit
  • Appendix C. Programming with the Java 2 Software Development Kit
  • Appendix D. Using Sun ONE Studio
  • Appendix E. Where to Go from Here: Java Resources
  • Appendix F. This Book's Web Site

Hour 12. Making the Most of Existing Objects

This might be a surprise to you, but your Java objects are ideally suited for childbearing. When you create a program as an object—a set of attributes and behavior—you have designed something that's ready to pass these qualities on to offspring. Like most offspring, these child objects will take on a lot of the attributes and behavior of their parent. They can also do some things differently than their parent does; some extra attributes and behavior can be added that Pop is incapable of.

This system is called inheritance, and it's something every superclass (parent) gives to its subclasses (children). Inheritance is one of the most useful aspects of object-oriented programming, and you'll be learning more about it during this hour.

Another useful aspect of object-oriented programming is the capability to create an object that can be used with different programs. Reusability speeds up the software development process and makes it easier to develop error-free, reliable programs. Using Java and special development tools, you'll be able to develop JavaBeans—completely reusable Java objects that are easily incorporated into programs.

The following topics will be covered:

• Superclasses and subclasses
• An inheritance hierarchy
• Overriding methods
• Creating a subclass
• Developing JavaBeans

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