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
    • How Object-Oriented Programming Works
    • Objects in Action
    • What Objects Are
    • Understanding Inheritance
    • Building an Inheritance Hierarchy
    • Converting Objects and Simple Variables
    • Workshop: Creating an Object
    • Summary
    • Q&A
    • Quiz
    • Activities
  • Hour 11. Describing What Your Object Is Like
  • Hour 12. Making the Most of Existing Objects
  • 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

Q&A

1. Can classes inherit from more than one class?

   It's possible with some programming languages, but not Java. Multiple inheritance is a powerful feature, but it also makes object-oriented programming a bit harder to learn and use. Java's developers decided to limit inheritance to one superclass for any class, although a class can have numerous subclasses. One way to compensate for this limitation is to inherit methods from a special type of class called an interface. You'll learn more about interfaces during Hour 19, "Creating a Threaded Program."

2. Why are object-oriented programs easier to debug?

   Object-oriented programs enable you to focus on a smaller part of a computer program when figuring out where an error is happening. Because a related group of tasks are handled by the same object, you can focus on that object if the tasks aren't being performed correctly. You don't have to worry about any other parts of the program.

3. When would you want to create a class that isn't public ?

   The main time you would not want to make a class of objects available to other programs is when the class is strictly for the use of one program you're writing. If you're creating a game program and your ReloadRayGun class of objects is highly specific to the game you're writing, it could be a private class. To keep a class from being public, leave off the public statement in front of class.

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