Vacationing in Java: A Tour of What Java Can Do
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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 Firefox, and the Opera browser can run Java programs that are found on web pages.
Load your browser software of choice, put on your best batik shirt, and get ready to take a vacation. 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
First Stop: Sun Microsystems
The Java vacation begins at a place you’ll be visiting regularly, now that you’re a Java programmer: the website 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, which you can try by visiting the web page at http://java.sun.com/openstudio. 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 website offers several Java programs for use on your own website.
Sun’s Java site is the place to find the latest released versions of the Java Development Kit as well as other programmer’s resources. This site offers announcements about Java-related products, full documentation for Java, and discussion forums where programmers can help each other as they learn the language. Sun Microsystems first made Java available for free via this website in 1995, and it’s still the first place to look for each new version of the language and Java Development Kit upgrade.
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 that would serve as the brains for smart appliances (interactive TVs, omniscient ovens, SkyNet military satellites with artificial intelligence that enslave mankind—you get the idea). 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.
Gosling named his new 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, and ReplayTV 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 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 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 six major releases of the Java language:
Fall 1995: Java 1.0—The original release
Spring 1997: Java 1.1—An upgrade to the language that improved the way user interfaces are created and handled
Summer 1998: Java 2 version 1.2—A version more than three times as large as Java 1.0, making 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
Spring 2002: Java 2 version 1.4—A substantial upgrade expanded Internet support, XML capabilities, and text processing
Spring 2004: Java 2, version 5—The current release, which makes programs more reliable and easier to write through additions such as automatic data conversion