What is JAVA

Java is a Computer Programming Language which is used all over the world. Using Java , we can design highly efficient, multipurpose programs. Java is widely used in programming industry.Java is an Platform Independent Programming Language that follows the principle WORA(Write Once Run Anywhere).

James Gosling along with the Mike Sheridan, and Patrick Naughton started the Java Project. Java was designed by keeping in mind the features of C and C++. Java is a object oriented language with the many features that help developers to develop efficient Applications. Java was called as Oak initially. Later they changed the name to Java.The first implementation of Java was released in 1995, java version 1.0. Initially it was having network and security features. Later than most of the browsers adapted Java applet features

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1.Simple- According to Sun MicroSystem, the company that developed Java Programming Language, but now owned by Oracle Corporation, Java is very simple because the syntax of the Java is very similar to it's previous Object oriented language C++ some concepts like pointers, operator overloading was removed. new feature that was not present in C++ is Automatic Garbage Collection.

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2.Object-Oriented- Just like it's predecessor C++, java is also an Object Oriented language. Object Oriented means, the code and data is arranged in different types of Objects and Classes.

Object Oriented Programming involves various concepts.

• Class
• Object
• Inheritance.
• Polymorphism
• Abstraction
• Encapsulation.

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3.Portable(Platform Independent) - Java is Platform Independent language means it can be run on any Operating System Platform. But Java is Software based platform Independent not Hardware Based. Java software runs on any hardware Platform.

It has following Components.<\nt>

• Java Runtime Environment(JRE).- is a Physical entity that contains software tools for developing Java Applications along with class libraries, JVM and other libraries.
• Java Development Kit(JDK). It is also a physical entity. It is combination of JRE plus all other development tools and libraries including compilers and debugers.
• Java Virtual Machine(JVM)- is the main entity to make the Java Portable Language, Write Once Run Anyware (WORA).JVM does'nt understand source code but bytecode.

That's why Java source file *.java needs to convert in class file *.class. which contains bytecode.

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4.Secured- Java is considered as most secured language. Because of following Components. Java does not include concept of pointers. The JVM Provides the security by running Java programs inside Virtual Machine Environment. Java Security Manager takes care of Security by making sure that untrusted code should not be allowed to execute.It manages and controls resources accessed by Programs, classes. for example, reading and writing to a file on local disk. etc.

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5.Robust- means tough and strong. Java is strongly typed language. Java's strong memory management and absence of pointers in Java ensures the tight security.

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6.Multi-threaded - A thread is nothing but a separate process or program running co-currently with another programs. We can write Java programs using Threads which can deal with multiple task simultaneously. Threads share the common memory area preventing load on the System. Threads are important part of Java.

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Writing Java Programs

Java programs are written in any simple text editor. The text file containing Java Source Code is saved with *.java extension. Then to compile the file , javac compiler is used. it compiles the file and generates the *.class file. *.class file is nothing but a file containing bytecodes instead of machine code. Then the JVM runs the application with instance of Java.
We can copy this *.class file on any System or Platform having Java Virtual Machine and run. It will generate the same output on all platforms.
Java Platforms.


1.Java SE.(Standard Edition). It is a nothing but a core Java. It contains all the libraries, tools,API which are very basic and every beginner should learn first before going in further.

2.Java EE(Enterprise Edition). This edition of Java contains more Advanced API ,libraries for development of large scale and commercial applications. It provides the support and libraries for Java Database Connectivity (JDBC), remote method invocation(RMI), webservice and all. Also contains API for Servlets,Java Beans, Java Server Pages. etc.

3.Java ME(Micro Edition). Micro edition as name suggest used for developing applications for mobile devices. Also contains API and libraries for Embedded Systems development. Micro Edition can be considered as Small subset of Java SE containing tools for mobile applications development.