What is Java and Its basic features ?

Java technology is both a programming language and a platform also. Which can be used to write and run java programs.

Features of Java :

1 Simple, Object Oriented, and Familiar

Java programming language is a simple language that can be programmed without extensive programmer training.

The Java programming language is designed to be object oriented from the ground up. The needs of distributed, client-server based systems coincide with the encapsulated, message-passing paradigms of object-based software. To function within increasingly complex, network-based environments, programming systems must adopt object-oriented concepts. Java technology provides a clean and efficient object-based development platform.

Even though C++ was rejected as an implementation language, keeping the Java programming language looking like C++ as far as possible results in it being a familiar language, while removing the unnecessary complexities of C++. Having the Java programming language retain many of the object-oriented features and the "look and feel" of C++ means that programmers can migrate easily to the Java platform and be productive quickly.

2 Robust and Secure

The Java programming language is designed for creating highly reliable software. It provides extensive compile-time checking, followed by a second level of run-time checking.

There are no explicit programmer-defined pointer data types, no pointer arithmetic, automatic garbage collection and excellent mechanism for exception handling that makes it a robust programming language. You can write the programs without worrying about memory leak etc.  

ava technology is designed to operate in distributed environments, which means that security is of paramount importance. With security features designed into the language and run-time system, 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.

3 Architecture Neutral and Portable

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, the Java Compiler ^TM product 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.

4 High Performance

Performance is always a consideration. The Java platform achieves superior performance by adopting a scheme by which the interpreter can run at full speed without needing to check the run-time environment. 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. 

5 Interpreted, Threaded

The Java interpreter can execute Java bytecodes directly on any machine to which the interpreter and run-time system have been ported. 

Modern network-based applications, such as the HotJava ^TM Browser for the World Wide Web, typically need to do several things at the same time. A user working with HotJava Browser can run several animations concurrently while downloading an image and scrolling the page. Java technology's multithreading capability provides the means to build applications with many concurrent threads of activity. Multithreading thus results in a high degree of interactivity for the end user.