Introduction to JAVA : JAVA Programming by "Gopal Krishna"

What is Java All About?

Java is an object-oriented programming language with a built-in application programming interface (API) that can handle graphics and user interfaces and that can be used to create applications or applets. Because of its rich set of API's, similar to Macintosh and Windows, and its platform independence, Java can also be thought of as a platform in itself. Java also has standard libraries for doing mathematics.
Much of the syntax of Java is the same as C and C++. One major difference is that Java does not have pointers. However, the biggest difference is that you must write object oriented code in Java. Procedural pieces of code can only be embedded in objects. In the following we assume that the reader has some familiarity with a programming language. In particular, some familiarity with the syntax of C/C++ is useful.

In Java we distinguish between applications, which are programs that perform the same functions as those written in other programming languages, and applets, which are programs that can be embedded in a Web page and accessed over the Internet. Our initial focus will be on writing applications. When a program is compiled, a byte code is produced that can be read and executed by any platform that can run Java.

To use this tutorial you should run and study each program as you read along, so that you can see how added features affect the programs.

History
Java is a programming language created by James Gosling from Sun Microsystems in 1991. The first publicly available version of Java (Java 1.0) was released in 1995.
Over time new enhanced versions of Java have been released. The current version of Java is Java 1.7 which is also known as Java 7.
From the Java programming language the Java platform evolved. The Java platform allows software developers to write program code in other languages than the Java programming language and still runs on the Java virtual machine. The Java platform is usually associated with the Java virtual machineand the Java core libraries.

So Java is:

 Object Oriented

 Platform independent:

 Simple

 Secure

 Architectural- neutral

 Portable

 Robust

 Multi-threaded

 Interpreted

 High Performance

 Distributed

 Dynamic with the implicit plus of complete portability.