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The Website Design and Promotion SIG met: September 1st, 2001, at the American Indian Center, 1630 West Wilson Avenue in Chicago. The meeting was conducted by Allen J. Kapusta, SIG member and presenter.
Java Programming Language
Presentation Summary by Allen J. Kapusta
The presentation for the September 1 meeting of the Web Design and
Promotion SIG was given by Allen Kapusta on the programming language
Java and its use in Internet and Web design. Java is a programming
language developed by Sun Microsystems. It is an object-oriented
language, which means it provides encapsulation (properties - data
values - and the methods - procedures - that manipulate them are
combined in an entity called an object), inheritance (a class - a "data
type" for objects with the same methods and with properties that have
the same characteristics - can inherit properties and methods from a
single class - the "superclass" of that class - and method names, but
not implementations, from multiple interfaces), and polymorphism (a
method may do things differently for different classes).
Java has a syntax similar to C and C++, but there are major differences
in the features of Java and C or C++. Instead of the pointers
(addresses) used in C, Java uses references and does not allow
arithmetic on references. Java does not allow the redefinition
(overloading) of operators, as C does. While C allows any data value to
be cast (reclassified) to any data type, Java allows only a specific set
of casting of primitive data types, and limits casting of objects to
superclasses of the object's class.
Java programs are converted to "bytecodes": machine language
instructions for a Java Virtual Machine (a specification for a
hypothetical machine), and interpreted and processed by an
implementation of the virtual machine for each real variety of computer
and operating system. This allows Java programs to be machine- and
platform independent. The Java Virtual Machine was designed to make it
easier to verify that a program is running correctly: array subscripts
and references to objects are checked to make sure that they are valid,
and access to files and communication channels are checked for security
authorization. The virtual machine also provides built-in storage
management (garbage collection) - this reduces "memory leaks" in which
storage is allocated but never released; this is done as a low-priority
process that is "transparent" to the programmer. The bytecode produced
for a Java program is smaller than the machine code that would be
produced by a conventional compiler, but the program runs slower than a
compiled program would.
Java provides advantages for Internet-based programs. The same program
will run on any client (browser): for a conventional compiled program,
to distribute 20 programs for 8 types of computer, you would need to
distribute 160 code files, but with Java bytecode you would need to
distribute 8 virtual machines (if the browsers were not already Java
capable), and 20 code files. Java can be used both for client-side
(browser-side) programs and server-side programs, so the same debugging
environment can be used for both sides of a client-server application.
Java has built-in support for Internet access using HTTP protocol,
connection-oriented error-free protocol, or raw IP packets (datagrams)
which can be lost, duplicated, or arrive out of order. Java also has
security features that protect against an Internet site from downloading
a program that can access your files and send back sensitive
information.
For further information, visit the Sun Microsystems web site at
java.sun.com, which has information and tutorials for programming in
JAVA as well as downloadable files for supporting Java development: the
Java Runtime Environment (including the Java Virtual Machine), the Java
Development Kit (currently Java 2 Software Development Kit), the Java
Servlet Development Kit, and Project Jakarta (named after a city on the
island of Java in Indonesia), which is an Apache (web server)
open-source verifier and translator for Java Server Pages. There are
also many books on Java, including
* Deitel, Harvey M. and Paul J. Deitel, Java How to Program
(currently third edition), Prentice-Hall, 1999, ISBN 0-13-012507-5,
includes CD-ROM with Java 2 SDK 1.2.1, Borland JBuilder 3 (University
Edition), and NetBeans DeveloperX2 2.1, priced at around $60 to $65
(version with second CD-ROM with examples from the book plus additional
examples, around $125)
* Sams.net, Java Unleashed, 1996, ISBN 1-57521-049-5, $49.99
* Flanagan, Daniel, et al., Java in a Nutshell, O'Reilly, ISBN
1-56592-262-X
* Exploring Java, O'Reilly
The presentation included a demonstration of a Java applet (a program
executed from within a browser) that shuffles and deals images
representing playing cards, with an explanation of what the source
programs do.
Meetings of The Chicago Computer Society - Web Development / Promotion SIG
are 1:00 pm. until 3:00 pm. at the American Indian Center, 1630 W. Wilson.
Beginners are invited to learn Internet Basics from 12:00-1:00 before each meeting.
We want your ideas! E-mail all future meeting topic requests for the Web Development / Promotion SIG meeting to: umcac@art-teez.org
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