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
    • First Stop: Sun Microsystems
    • Going to School with Java
    • Lunch in JavaWorld
    • Taking in a Ballgame at ESPN.com
    • Getting Down to Business
    • Stopping by Gamelan to Ask Directions
    • Workshop: Putting Java on Your Desktop
    • Summary
    • Q&A
    • Quiz
    • Activities
  • 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
  • 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

First Stop: Sun Microsystems

The Java vacation begins at a place you'll be visiting regularly, now that you're a Java programmer: the Web site of Sun Microsystems, the company that developed the Java language. To get there, go to http://java.sun.com.

A Java program that runs as part of a Web page is called an applet. Applets are placed on pages like other elements of a page—a markup language called HTML is used to define where the program should be displayed, how big it is, and what the program does when it runs.

The Java division of Sun Microsystems is responsible for the advancement of the Java language and the development of related software. As you might expect of a proud parent, Sun uses Java applets on its site. There's a glossary applet that's a guide to the site, several applets that are free for your own use, and others.

The sample applets include an animated clock and a shopping cart assistant. Java can be a great attention-getter, creating content dynamically that changes as a page is being viewed in a Web browser. Figure 3.1 shows the clock and other sample applets.

Figure 3.1 Sun's official Java Web site offers several Java programs for use on your own Web site.

Sun's Java site is the place to find the latest released versions of the Software Development Kit, as well as other programmer's resources. This site also has press releases about Java-related products, full documentation for Java, and sample Java programs that run on the Web. Sun Microsystems first made Java available for free via this Web site in 1995, and it's still the first place to look for each new development kit and addition to the language.

A Brief History of Java

Sun co-founder Bill Joy called Java "the end result of fifteen years of work to produce a better, more reliable way to write computer programs." Java's creation was a little more complicated than that.

Java was developed in 1990 by Sun engineer James Gosling as a language to use as the brains for smart appliances (interactive TVs, omniscient ovens, and the like). Gosling was unhappy with the results he was getting by writing programs with C++, another programming language, so he holed up in his office and wrote a new language to better suit his needs.

At the time, Gosling named his language Oak after a tree he could see from his office window. The language was part of Sun's strategy to make millions when interactive TV became a multimillion-dollar industry. That still hasn't happened today (though TiVo, ReplayTV, and WebTV are making a game attempt), but something completely different took place for Gosling's new language. Just as Sun was ready to scrap Oak development and scatter its workers to other parts of the company, the World Wide Web became popular.

In a fortuitous circumstance, many of the qualities that made Gosling's language good on its appliance project made it suitable for adaptation to the World Wide Web. Sun developers devised a way for programs to be run safely from Web pages and chose a catchy new name to accompany the language's new focus: Java.

Although Java can be used for many other things, the Web provided the showcase it needed to capture international attention. A programmer who puts a Java program on a Web page makes it instantly accessible to the entire Web-surfing planet. Because Java was the first technology that could offer this capability, it became the first computer language to receive star treatment in the media. When the language really rose to prominence in 1996, you had to be in solitary confinement or a long-term orbital mission to avoid hearing about Java.

There have been five major releases of the Java language:

• Fall 1995: Java 1.0— A version best suited for use on the World Wide Web that showed potential for expansion into other types of programming
• Spring 1997: Java 1.1— An upgrade to the language that included numerous improvements to the way user interfaces are created and handled
• Summer/Fall 1998: Java 2, version 1.2— A version more than three times as large as Java 1.0, with enhancements that make the language a worthy competitor to other general-purpose programming languages
• Fall 2000: Java 2, version 1.3— A release supporting faster running Java programs and enhanced multimedia features, as well as the first official support for Java development on the Linux operating system
• Spring 2002: Java 2, version 1.4— A substantial upgrade with a much-requested feature called assertions to improve software reliability, expanded networking support, and XML processing

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