Vacationing in Java
Before you venture further into Java programming, it's worthwhile to learn more about the language and see what Java programmers are doing today. One of the reasons that Java became popular so quickly was because it could be used to offer programs on the World Wide Web. Though Java has outgrown its origins as a language focused on Web programs, you can still find some interesting examples of how Java is used on the Web.
During this hour, we'll take a look at some sites that feature Java programs and talk about the history and development of the language.
To go on this vacation, you need a Web browser that can handle Java programs. The current versions of Microsoft Internet Explorer, Mozilla, Netscape Navigator, and the Opera browser can run Java programs that are found on Web pages.
If you're using a current version of Netscape Navigator or Microsoft Internet Explorer and it isn't working with Java programs, check your setup configuration from one of the program's pull-down menus. Make sure your browser software has Java enabled in its settings.
Load your browser software of choice, put on your best batik shirt, and get ready to vacate. Because you won't be leaving your house, you won't get a chance to experience the simpler pleasures of tourism: odd driving rituals, exotic food, exotic members of the opposite sex, exotic members of the opposite sex with food, and so on. But look on the bright side: no antibacterial shots, traveler's checks, or passports are required either.
The following topics will be covered during this hour:
A definition of the Java language
The benefits of using Java
Some examples of Java at work
An explanation of object-oriented programming
Sites of note for Java programmers
The sightseeing examples you visit during today's vacation are just a small sampling of the Java programs in use on the Web. A search of the AltaVista Web search database finds more than 7.8 million pages that have included a Java program as of this writing.
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 pagea 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.
Today, many of us like writing programs with Java, so we have no incentive to create our own programming languages. As a result, we have more time to hole up in our offices and play EverQuest instead.
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.
You might have heard that Java is an acronym that stands for Just Another Vague Acronym. You also might have heard that it was named for the developers' love of coffee, especially the percolating product from a shop near Sun's offices. Actually, the story behind Java's naming contains no secret messages or declarations of liquid love. Instead, Java was chosen for the same reason that comedian Jerry Seinfeld likes to say the word salsa. It sounds cool.
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 1.0A version best suited for use on the World Wide Web that showed potential for expansion into other types of programming
Spring 1997: Java 1.1An upgrade to the language that included numerous improvements to the way user interfaces are created and handled
Summer/Fall 1998: Java 2, version 1.2A 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 1.3A 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 1.4A substantial upgrade with a much-requested feature called assertions to improve software reliability, expanded networking support, and XML processing