Java is always an interesting language to learn and work on as compared with nay other programming languages. The enablers to the mentioned are that java is fast and is very interactive language. By programming to the Java Platform, you can develop and deploy applications to desktops and servers, as well as to today’s demanding embedded and real-time environments. In addition, the Java platform includes support for the development of simple and complex web applications and services.Java technology is both a programming language and a platform. The designers of Java chose to use a combination of compilation and interpretation. Programs written in Java are compiled into machine language, but it is a machine language for a computer that doesn’t really exist. This so-called “virtual” computer is known as the Java virtual machine. The machine language for the Java virtual machine is called Java bytecode. There is no reason why Java bytecode could not be used as the machine language of a real computer, rather than a virtual computer.However, one of the main selling points of Java is that it can actually be used on any computer.
The Java Programming Language
The Java programming language is a high-level language that can be characterized by all of the following buzzwords:
SimpleIn 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 javac compiler.
Architecture neutral
Object oriented
Portable
Distributed
High performance
Multithreaded
Robust
Dynamic
Secure
A .class file does not contain code that is native to your processor; it instead contains bytecodes � the machine language of the Java Virtual Machine1 (Java VM). The java launcher tool then runs your application with an instance of the Java Virtual Machine.
Because the Java VM is available on many different operating systems, the same .class files are capable of running on Microsoft Windows, the Solaris TM Operating System (Solaris OS), Linux, or Mac OS.
Some virtual machines, such as the Java HotSpot virtual machine, perform additional steps at runtime to give your application a performance boost. This include various tasks such as finding performance bottlenecks andrecompiling (to native code) frequently used sections of code.
The Java Platform
A platform is the hardware or software environment in which a program runs. We’ve already mentioned some of the most popular platforms like Microsoft Windows, Linux, Solaris OS, and Mac OS. Most platforms can be described as a combination of the operating system and underlying hardware. The Java platform differs from most other platforms in that it’s a software-only platform that runs on top of other hardware-based platforms.
The Java platform has two components:
The Java Virtual Machine
The Java Application Programming Interface (API)
You’ve already been introduced to the Java Virtual Machine; it’s the base for the Java platform and is ported onto various hardware-based platforms.
The API is a large collection of ready-made software components that provide many useful capabilities. It is grouped into libraries of related classes and interfaces; these libraries are known as packages. The next section, What Can Java Technology Do? highlights some of the functionality provided by the API.
The API and Java Virtual Machine insulate the program from the underlying hardware.
As a platform-independent environment, the Java platform can be a bit slower than native code. However, advances in compiler and virtual machine technologies are bringing performance close to that of native code without threatening portability.
