Java Reference
In-Depth Information
Perhaps the most important element in Java's success was its timeli-
ness. The language was introduced at the same time that the World Wide
Webwas rapidly gaining popularity. The Webis an international network
of incompatible computers, made by dozens of manufacturers and having
unique hardware characteristics. There is no standard operating system
or software environment on the Web.
Java brought a promise of uniformity and compatibility to this diverse
hardware and software environment of often irreconcilable differences.
Its promise was that a program written in the Java language would exe-
cute correctly on any Java-enabled machine. A Java programmer could
code a small application, embed it in a Web page, and the program would
run on any browser that supported Java.
Programmers note:
The language used to create Webpages and other Internet documents
is called
Hypertext Markup Language
(HTML). Java code can be em-
bedded in HTML documents in a capsule called a Java
applet
.
Java also provides a way of extending the functionality of a Web
browser. Using Java, you can create a Web page that does more than is
possible with straight HTML. The processing is contained in a Java applet
that runs on any Java-enabled browser, including Mosaic, Netscape Navi-
gator, or Internet Explorer. The applet executes correctly on a PC run-
ning Windows, on a Macintosh, on a UNIX machine, or on an IBM
mainframe. The result is the same if you are connected to the Internet
through a high-speed network or a slow-speed modem. This is what
makes Java powerful and unique.
The Portability Issue
In computer talk, the word “portable” describes code that can be moved to
varioussystemswithlittleornoeffort.Theexpressionprobablyrelatestoa
computer connection, called a port, that is used for passing data in and out
of a machine. Code that can be made to work in another machine simply by
sending it through ports, is said to be
portable
. A programming language,
suchasJava,thatcanbeeasilymadetorunonvarioussystemsisdescribed
as highly portable.
Originally, Java's portability was limited to applets intended for the
Web. It was soon noticed that Java could be used as a full-featured pro-
gramming language to develop complete applications. The resulting pro-
grams would be portable to any Java-supporting platform. The benefits of
