Friday, January 18, 2013

What is Java ? : Introduction to Java Language

What is Java ? or Introduction to Java Language

Java is a general-purpose, concurrent, class-based, object-oriented computer programming language that is specifically designed to have as few implementation dependencies as possible. It is intended to let application developers "write once, run anywhere" (WORA), meaning that code that runs on one platform does not need to be recompiled to run on another. Java applications are typically compiled to byte code (class file) that can run on any Java virtual machine (JVM) regardless of computer architecture. Java is, as of 2012, one of the most popular programming languages in use, particularly for client-server web applications, with a reported 10 million users. Java was originally developed by James Gosling at Sun Microsystems (which has since merged into Oracle Corporation) and released in 1995 as a core component of Sun Microsystems' Java platform. The language derives much of its syntax from C and C++, but it has fewer low-level facilities than either of them.

The original and reference implementation Java compilers, virtual machines, and class libraries were developed by Sun from 1991 and first released in 1995. As of May 2007, in compliance with the specifications of the Java Community Process, Sun relicensed most of its Java technologies under the GNU General Public License. Others have also developed alternative implementations of these Sun technologies, such as the GNU Compiler for Java and GNU Classpath.

About Java Language

Java is OOPS language, it supports OOPS features…
  • Data encapsulation
Encapsulation is the mechanism that binds the code and the data it manipulates, keeps safe from both out side inheritance and misuse.
  • Inheritance
Inheritance is the process by which one object`s properties are acquired and used by other object. In short code re-usability. It is achieved by extends keyword in Java.
  • Polymorphism
In short Polymorphism mean many forms, one interface will be used for many tasks. This will be explained detailed with example.
…These are few among them..

Java program starts with class and main method will be included in the class.
Unlike C,C++ in java main method will pass String. Lets go to an example.


public static void main(String args[])



public keyword is access specifier, which allows the programmer to control visibility of class members.

Keyword static allows main() to be called with out having to instantiate by particular instance(object) of a class, this is necessary since main() is called by JVM (Java virtual machine) before any objects are made.

String args[] declares parameter args, which is an array of instances in class String.(Arrays are collection of similar objects).

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