What s java ( topic from mufix face book)

**What is java??

java refers to a combination of three things:
1-the Java programming language (a high-level, object-oriented
programming language)
2- the Java Virtual Machine (a high-performance virtual machine
that executes byte codes on a specific computing platform,
JVM)
3- and the Java platform

# High level language :
a language that is easily understandable to human ( English
statements )

# object-oriented programming language (OOPL) :
A type of programming in which programmers define not only the
data type of a data structure, but also the types of operations
(functions) that can be applied to the data structure. In this way,
the data structure becomes an object that includes both data and
functions. In addition, programmers can create relationships
between one object and another. ( we will discuss it in details
later).

# JVM (Java Virtual Machine) :
is a set of computer software programs and data structures which
use a virtual machine model for the execution of other computer
programs and it accepts java byte code and converts it into
machine language and executes it .
It enabling Java byte code to be executed as actions or operating
system calls on any processor regardless of the operating system.

# Byte code : a special machine language that can be understood by
the Java Virtual Machine and it is normally (but not necessarily)
generated from Java source code;

# Java platform : Java refers to a number of computer software
products and specifications from Sun Microsystems that together
provide a system for developing application software ( J2ME ,
J2SE , J2EE)


** Wanna know more about java let's see:

Java let us do things on web page that you couldn't do before like :

1- Play a sound whenever a user visits a page.
2-Play music in the background while the user reads a page
3-Use vector graphics instead of bitmaps and GIFs
4-Run animation sequences in real time.
5-Create forms that verify the user's input.
6-Create real-time multiplayer interactive games

Java changes the Web from a static, fixed medium to a real-time interactive, dynamic, expandable multimedia environment.

We also can use it in :
-desktop applications
-mobile applications
-graphics and games



**Why java better than the others??

1-It is easier to program and to learn than Fortran, Basic or C++
and it can do almost anything they can do.

2-Java has garbage collection : responsible for freeing any memory
that can be freed. This happens automatically during the lifetime
of the Java program.

3-Java is simple, it is easy to read and write

4-Java is interpreted so the compile-link-run cycle is much shorter.
(In fact, the link phase is eliminated entirely)

5-Java is object-oriented (unlike Basic) that makes programs
Simpler, and easier to read and make more efficient reuse of
Code

6-Java is Platform Independent :
( Write Once, Run Anywhere ) , write your application once for
the Java platform and then you'll be able to run it anywhere.

7-Java is Safe :
The Java platform allows users to download untrusted code over a
network and run it in a secure environment in which it cannot do
any harm, it cannot infect the host system with a virus, cannot
read or write files from the hard drive, and so forth. This
capability alone makes the Java platform unique.

8-Java is High Performance :
The Java Virtual Machine runs a Java program by interpreting
these portable byte-code instructions. This architecture means
that Java programs are faster than programs or scripts written in
purely interpreted languages

9-Java is Multi-Threaded : single Java program can have many
different processes executing independently and continuously.

10-Java is Dynamic :
Java code is organized in modular object-oriented units called
classes. Classes are stored in separate files and are loaded into
the Java interpreter only when needed. This means that an
application can decide as it is running what classes it needs and
can load them when it needs them. It also means that a program
can dynamically extend itself by loading the classes it needs to
expand its functionality.


## References :

http://docstore.mik.ua/orelly/java-ent/jnut/ch01_02.htm

http://en.wikipedia.org/wiki/Java_(programming_language)

http://www.onjava.com/pub/a/onjava/2006/03/08/what-is-java.html

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