Java

views updated May 29 2018

JAVA

Java is a programming language that is widely used on the World Wide Web, both in Web pages (client side) and on Web servers (computers used to host or maintain Web sites). Therefore, it is an important technical component of e-commerce. Based on a high-level programming language called C++, the most popular, powerful aspect of Java is that it allows programmers to create programs that can be downloaded onto computers regardless of their operating systems (programs like Windows used for controlling a computer's basic operations). Additionally, because of its available security features, programs written in Java can be downloaded and run safely, eliminating concerns about viruses or damaged files.

Java is both simple and powerful, which makes it popular with programmers. Like C++, it is an object-oriented programming language. Object-oriented programming involves techniques that allow programmers to increase efficiency and reduce complexity. Java was developed by Sun Microsystems in 1991 for use in consumer devices. However, it soon found a place on the Web when Sun made it available for that purpose in the mid-1990s. In the early 2000s, Web browsers like Netscape Navigator, cellular phones, and personal digital assistants were being specifically designed to support the Java programming language.

HOW JAVA WORKS

Because it is an interpreted language, Java doesn't work alone. It relies on an interpreter called the Java Virtual Machine (JVM) to function. Many high-level programming languages, like C and C++, rely on programs called compilers or interpreters so they can be converted to the fundamental machine language (zeroes and ones) that a computer's hardware actually understands. However, instead of being translated directly into machine language, programs written in Java are compiled into bytecode—an intermediate language that can be interpreted by any computer running JVM. This is what gives the Java language the ability to run on any computer. While the Java programming language is available for free to programmers, the JVM requires a license for use.

Besides JVM, the Java language relies on another critical component known as the Java Platform. As David Flanagan explained in Java in a Nutshell, the Java platform consists of a set of classes. "A class is a module of Java code that defines a data structure and a set of methods (also called procedures, functions, or subroutines) that operate on that data." Classes are subsequently organized into groups called packages, which involve many functions, including networking, graphics, input/output, user-interface creation, and security.

When programs written in Java run from a Web page, they are referred to as applets. When they run on servers, they are referred to as servlets. Rather than running from a server, Web page applets actually get downloaded to a user's computer, sometimes in a matter of seconds. This frees up the server's resources so its efficiency is not affected. Many applets are available to Web site operators for free. Examples of applets include productivity tools like spread sheets, animation, mathematical applications like calculators, Web forms, and more. Many applets can be valuable tools on e-commerce sites. Because they are actual programs, applets allow Web site operators to expand the capabilities of their sites beyond that which is possible with hypertext markup language (HTML)—the authoring or presentation language used for creating the appearance of Web pages.

Like most programming languages, Java has evolved since it first came onto the scene. Since the mid-1990s, several improved versions have been released. Although other languages like Visual Basic were easier to learn, there was a very strong interest in Java during the early 2000s. At that time, hundreds of books had been written on the language, and it was poised to play an increasing role on the World Wide Web. Some industry professionals expected Java to become the dominant programming language of the 2000s.

Java

views updated May 21 2018

Java A language for object-oriented programming on the Internet, especially applicable to the World Wide Web; it was developed from 1990 at Sun Microsystems by P. Naughton. The output produced by a Java compiler is not executable code but an intermediate representation, known as bytecode, that is designed to translate directly into native machine code for high performance. Bytecode can thus be interpreted on any computer on which the Java run-time system is installed, allowing cross-platform portability (see platform, portable). Allegedly, full security is provided as no Java program can break out of this run-time environment or access unprotected system resources. Java is optimized for small networked applications that are dynamically downloaded across the Internet. These small programs, known as applets, can react to user input.

A Dictionary of Computing JOHN DAINTITH

Java

views updated May 09 2018

Java Indonesian island, between the Java Sea and the Indian Ocean, se of Sumatra; its largest city is Jakarta. In the early centuries ad, the island was ruled by Hindu kingdoms. Islam began to spread in the 16th century. By the 18th century the island was mainly under Dutch control. It was occupied by the Japanese during World War II. Java is a mountainous country, with a volcanic belt in the s and an alluvial plain to the n. It is thickly forested and has many rivers. It produces rice, tea, coffee, sugar cane, textiles, tobacco, and rubber. Silver, gold, and phosphate are mined in the n. Area: 126,501sq km (48,842sq mi). Pop. (2000) 117,319,419.