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JAVA
Introduction:What is java?
Java-As a Programming Language: The java is a high-level, object-oriented and general-purpose
computer programming language.
 Java is similar to c++, but simplified to eliminate language features
that cause common programming errors.
 you can use java to write computer applications that play games,
store datax or do any of the thousands of other things computer
software can do.
Java-As a Computing Platform: Java has its own runtime environment (jre) and API, it is called a
platform.
 There are lots of applications and websites that will not work
unless you have java installed, and more are created every day.
 From laptops to datacenters, game consoles to scientific
supercomputers,cell phones to internet, Java is everywhere!
Where is Java used?
According to sun, 3 billion devices run java. There are many devices
where java is currently used. Some of them are as follows:
 Desktop Applications such as acrobat reader, media player, antivirus
etc.
 Web Applications such as irctc.co.in, javatpoint.com etc.
 Enterprise Applications such as banking applications.
 Mobile
 Embedded System
 Smart Card
 Robotics
 Games etc.
History Of Java:History of java
Java
High level programming
language
Distributed technology
James Gosling
At sun micro system
Implemented by java soft
INC, USA
Rules
1990
OAK (tree name)
(original name of java)
1995
(revised)
Java
 (coffee seed name)
The slogan of JAVA is “Write One’s Reuse/Run Anywhere”(WORA).
->Java is a “High level programming language” and it is a distributed technology.
->Developed by James Gosling, Patic Naughton etc., at sun micro system Has released lot
rules for java and implemented by java soft INC, USA in the year 1990.
->The original name of java is OAK (which is a tree name).
->In year 1995 OAK was revised and developed a software called java(which is a coffee
seed name).
RELEASED CATEGORIES OF JAVA :Java released to the market in three categories
 JSE(Java standard edition) and is normally for
developing desktop applications, forms the core/base
API.
 JEE(Java enterprise edition) for applications which run
on servers, for example web sites.
 JME(Java micro/mobile edition) applications which
run on resource constrained devices (small scale
devices) like cell phones for examples games.
JAVA
JSE
JME
JEE
JSE is basically used for developing client side application/program.
JEE is used for developing sever side application/program.
JME is used for developing sever side application/program.
JSE
J
E
E
E
J
M
E
E
If we want to exchange data from client to sever (jse &jee),by
default java is having on internal support called http.
Jme is used for developing mobile applications & lower/system level
applications. To develope jme applications we must use a protocol called WAP.
COMPONENTS OF JAVA:In java we have 3components they are :
JDK(Java development kit)
JRE(Java run time execution)
JVM(Java virtual machine)
JDK
JDK
JRE
+
Source
JVM+
Development
LIBRARY
Tools
JDK: Jdk is used to develope the source code. It is not use development but it
take care of execution & compilation.
 It physically exists.
 It contains Jre + development tools.
JRE: Jre is used only for execution. And it is the implementation of Jvm.
 It is physically exits.
 It contains jvm+ library.
JVM: Jvm is an abstract machine.
 Jvm are available for many hardware and software flat forms.
 Jdk, jre and Jvm are flat dependent because the configuration of each os
differs. But, java is a flat form independent.
The jvm performs the following main tasks:
i.
ii.
iii.
iv.
Loads code
Verifies code
Executes code
Provides runtime environment
FEATURES OF JAVA:i. Simple
ii.
iii.
iv.
v.
vi.
vii.
viii.
ix.
Platform independent
Open source
Secured
Portable
distributed
Roburst
Object-Oriented
Dynamic
SIMPLE:- Java contains user friendly syntax for developing java applications.
Java is easy to write and more readable and eye catching.
Platform independent:- A program or technology is said to be platform
independent if & only if which can run on all available os. The language like
java will have a common data types and the common memory spaces on all os.
Open source:- Open source means free licensed software means freely available
in the market.
Secured:- Java is a secured programming language .Means providing security
from third party. Java provide secure way to access web applications.
Portable:- A portable language is one which can run on all os & on all
processors irrespective their architecture &providers.
Distribute :- Java is distributed technology.
Robust:- Java encourages error-free programming by being strictly typed and
performing run-time checks.
Object-Oriented:-Java programming is Object-Oriented programming language.
Like c++ java provides most of the object oriented features. Java is pure oop
Language (while c++ is semi object oriented).
Dynamic:- Java programs carry with them substantial amounts of run-time type
information that is used to verify and resolve accesses to objects at run time.
Rules: Java is a case sensitive.
 The class name should be start with a capital letter it is not compulsory
but it is conventional rule.
 All keywords in java are written in small letters.
 If we want to write anything in java we have to create class. Means to
create anything in java class is compulsory needed.