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Java
Java is a programming language expressly designed for use in the distributed environment of the Internet. It was designed to have the "look and feel" of the C++ language, but it is simpler to use than C++ and enforces an object-oriented programming model. Java can be used to create complete applications that may run on a single computer or be distributed among servers and clients in a network. It can also be used to build a small application module orapplet for use as part of a Web page. Applets make it possible for a Web page user to interact with the page.
The major characteristics of Java are:
·
The programs you create are portable in a network. Your source program
is compiled into what Java calls bytecode, which can be run anywhere in a network on a
server or client that
has a Java virtual
machine.
The Java virtual machine interprets the bytecode into code that will run
on the real computer hardware. This means that individual computer
platform differences such as instruction lengths can be recognized and
accommodated locally just as the program is being executed.
Platform-specific versions of your program are no longer needed.
·
The code is robust,
here meaning that, unlike programs written in C++ and perhaps some other
languages, the Java objects can contain no references to data external
to themselves or other known objects. This ensures that an instruction
cannot contain the address of data storage in another application or in
the operating system itself, either of which would cause the program and
perhaps the operating system itself to terminate or "crash." The Java
virtual machine makes a number of checks on each object to ensure
integrity.
·
Java is object-oriented, which means that, among other characteristics,
an object can
take advantage of being part of a class of
objects and inherit code that is common to the class. Objects are
thought of as "nouns" that a user might relate to rather than the
traditional procedural "verbs." A method can
be thought of as one of the object's capabilities or behaviors.
·
In addition to being executed at the client rather than the server, a
Java applet has other characteristics designed to make it run fast.
·
Relative to C++, Java is easier to learn. (However, it is not a language
you'll pick up in an evening!)
Java was introduced by Sun Microsystems in 1995 and instantly created a
new sense of the interactive possibilities of the Web. Both of the major
Web browsers include a Java virtual machine. Almost all major operating
system developers (IBM, Microsoft, and others) have added Java compilers
as part of their product offerings.
The Java virtual machine includes an optional just-in-time
compiler that
dynamically compiles bytecode into executable code as an alternative to
interpreting one bytecode instruction at a time. In many cases, the
dynamic JIT compilation is faster than the virtual machine
interpretation.
JavaScript should
not be confused with Java. JavaScript, which originated at Netscape, is
interpreted at a higher level, is easier to learn than Java, but lacks
some of the portability of Java and the speed of bytecode. Because Java
applets will run on almost any operating system without requiring
recompilation and because Java has no operating system-unique extensions
or variations, Java is generally regarded as the most strategic language
in which to develop applications for the Web. (However, JavaScript can
be useful for very small applications that run on the Web client or
server.) | ||||||||||||||||||||||
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AIVELMECH S. ENCARNACION [email protected] |