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
    • Creating Variables
    • Creating Class Variables
    • Creating Behavior with Methods
    • Putting One Class Inside Another
    • Using the this Keyword
    • Workshop: Using Class Methods and Variables
    • Summary
    • Q&A
    • Quiz
    • Activities
  • 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

Hour 11. Describing What Your Object Is Like

As you learned during last hour's introduction to object-oriented programming, an object is a way of organizing a program so that it has everything it needs to accomplish a task. Objects need two things to do their jobs: attributes and behavior.

Attributes are the information stored within an object. They can be variables such as integers, characters, Boolean values, or other objects such as String and Calendar objects. Behavior is the groups of statements used to handle specific jobs within the object. Each of these groups is called a method.

Up to this point, you have been working with the methods and variables of objects without knowing it. Any time your statement had a period in it that wasn't a decimal point or part of a string, chances are an object was involved. You'll see this during this hour as the following topics are covered:

• Creating variables for an object
• Creating variables for a class
• Using methods with objects and classes
• Calling a method in a statement
• Returning a value with a method
• Creating constructor methods
• Sending arguments to a method
• Using this to refer to an object
• Creating new objects
• Putting one object inside another object

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