Definitions[edit | edit source]
|“||was developed by Sun, first released in 1996, and has become one of the world's most popular programming languages and platforms. The Java platform, through the use of a virtual machine, enables software developers to write programs that are able to run on different types of computer hardware without having to rewrite them for each different type. Programs that run on the Java platform are written in the Java language. Java was developed to run on desktop computers and enterprise servers.||”|
|“||[a] programming language developed by Sun Microsystems. Java contains a number of features that make it well suited for use on the World Wide Web.||”|
|“||a full-featured, object-oriented programming language compiled into platform-independent byte code executed by an interpreter called the Java Virtual Machine (JVM).||”|
Overview[edit | edit source]
The intent was to provide a universal programming language. Programs written in Java can run on any computer using a Java-compatible operating systems and can be downloaded safely from the Internet without the fear of viruses or other harmful programs.
The term Java actually refers to four interlocking components. First, there is a Java programming language with which developers can write applications. Second, there is a set of programs written in Java that expose APIs on which developers writing in Java can rely. These programs are called the “Java class libraries.” The third element is the Java compiler, which translates the code written by the developer into Java bytecode.
Finally, there are programs called “Java virtual machines,” or “JVMs,” which translate Java bytecode into instructions comprehensible to the underlying operating system. If the Java class libraries and a JVM are present on a PC system, the system is said to carry a “Java runtime environment.”
A program written in Java and relying only on APIs exposed by the Java class libraries will run on any PC system containing a JVM that has itself been ported to the resident operating system. Therefore, Java developers need to port their applications only to the extent that those applications rely directly on the APIs exposed by a particular operating system. The more an application written in Java relies on APIs exposed by the Java class libraries, the less work the developer will need to do to port the application to different operating systems. The easier it is for developers to port their applications to different operating systems, the more applications will be written for operating systems other than Windows.