Introduction to Java

Java is both a programming language and a platform ,

It is a high level language that is simple,object oriented, distributed, multithreaded, dynamic, architecture neutral, portable, robust and secure. In the Java programming language, all source code is first written in plain text files ending with the .java extension. Those source files are then compiled into .class files by the Java compiler (javac). A .class file does not contain code that is native to a processor; 

it instead contains bytecodes - the machine language of the Java Virtual Machine. The Java

launcher tool (java) then runs the application with an instance of the Java Virtual Machine.

The Java Virtual Machine is available on many different operating systems, the same .class files are capable of running on Microsoft Windows, the Solaris Operating System (Solaris OS), Linux, or MacOS. Some virtual machines,such as the Java HotSpot Virtual Machine, perform additional steps at runtime to give your 

application a performance boost.

The Java programming language is a high-level language that can be characterized by all of the following buzzwords:

1.Simple

2.Object oriented

3.Distributed

4.Multithreaded

5.Dynamic

6.Architecture neutral

7.Portable

8.High performance

9.Robust

10.Secure

1.Simple - 

simple language that can be programmed without extensive programmer training , syntax is simple and easy to understand , Familiar to C++. having "look and feel" of C++ and removed all the complexities of C++ , means that programmers can migrate easily to the Java platform and be productive quickly.

2.Object Oriented -

Java programming language is Object-Oriented, everything in java is object , we have to deal with objects.To Learn more about object , please click here.

3.Distributed -

Java is Distributed Language, it means ,because the program of java is compiled on one 
machine can be easily transferred to other machine and Executes them on another machine because 
facility of Bytes Codes So java is Specially designed For Internet Users which uses the 
Remote Computers For Executing their Programs on local machine after transferring the Programs from Remote Computers or either from the internet.

4. Multithreaded - 

multithreading capability helps to build applications with many concurrent threads of activity..we can perform multiple operations simultaneously ,in multithreaded application.

5.Dynamic - 

Java is considered as Dynamic because of Byte code [a class file]. A source code written
 in one platform, that can be executed in any platform. And it also loads the class files at run time. Anything that happens at run time is considered as Dynamic.run-time system are dynamic in their linking stages. Classes are linked only as needed. New code modules can be linked in on demand from a variety of sources, even from sources across a network. I

6.Architecture neutral -

the Java Compiler generates bytecodes - an architecture neutral intermediate format designed to transport code efficiently to multiple hardware and software platforms.

The interpreted nature of Java technology solves both the binary distribution problem 

and the version problem; the same Java programming language byte codes will run on any platform.

Java technology is designed to support applications that will be deployed into heterogeneous 

network environments. In such environments, applications must be capable of executing on a 

variety of hardware architectures. Within this variety of hardware platforms,

applications must execute atop a variety of operating systems and interoperate with 

multiple programming language interfaces. To accommodate the diversity of operating

environments.

7.Portable -

WORA-Write Once Read Anywhere.Java is known as a "portable language" because Java code can execute on all major platforms.What's more, once you've compiled your Java source to "byte-code" .class, those files can be used on any Java-supported platform without modification.

8.High performance -

Java platform achieves superior performance.The automatic garbage collector runs as a low-priority background thread, ensuring a high probability that memory is available when required, leading to better performance.Applications requiring large amounts of compute power can be designed such that compute-intensive sections can be rewritten in native machine code as required and interfaced with the Java platform. In general, users perceive that interactive applications respond quickly even though they're interpreted.

9.Robust- 

robust means strong and healthy,Java is a robust language that can handle run-time errors as it checks the code during the compile and runtime. If any runtime error is identified by the JVM,it will not be passed directly to the underlying system.

10.Secure-

Java technology lets you construct applications that can't be invaded from outside.

In the network environment, applications written in the Java programming language are secure 

from intrusion by unauthorized code attempting to get behind the scenes and create viruses 

or invade file systems.