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
  • 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
    • Using Graphics
    • Drawing Lines and Shapes
    • Workshop: Baking a Pie Graph
    • Summary
    • Q&A
    • Quiz
    • Activities
  • 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 23. Working with Graphics

Graphics can be represented on a computer in several ways. One way is to store the image using a file format that approximates what the graphic looks like. For example, if you took a photo of the Californian sasquatch swimming in your pool and scanned it into your computer, you could save it as a JPEG file. The JPEG format is ideal for storing photographic images in reasonably small file sizes.

You can also represent graphics as a series of drawing instructions used to create the image. These are called "vector graphics," and they are becoming popular on the World Wide Web in the form of Macromedia Flash programs. These graphics don't look like photographic images, but they are much smaller in file size and can be redrawn easily at different sizes, making them ideal for animation. If you created a cartoon about the sasquatch, you could save it in a vector format.

Java supports vector graphics through Java2D, the same classes that were used to draw text in different ways in Hour 21, "Using Fonts and Color." You'll get a chance to draw shapes of different colors in a program—everything from rectangles to ovals to lines.

The following subjects will be covered:

• The drawing methods of the Graphics2D class
• Drawing lines
• Drawing rectangles and rounded rectangles
• Drawing polygons
• Drawing ellipses
• Drawing with different colors
• Drawing filled and unfilled shapes

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