Java language Overview

First, the history of Java

1. What is Java

Silicon Valley in the United States has a jargon, every 10 years ~15 year there is a reincarnation. One of the most recent cycles is starting with Java.

Java is a new generation of programming languages developed by Sun Corporation. It can be used to develop software in a variety of different types of machines, different operating platforms of the network environment. No matter what kind of www browser you use, what kind of computer, which operating system, as long as the WWW browser noted "Support Java", you can see the Vivid homepage. Java is gradually becoming the main development language for Internet applications. It revolutionized the development model of application software and brought another technological revolution since the PC, adding new vitality to the rapidly growing information world.

Sun's Java language Development Group was founded in 1991 to develop consumer electronics markets such as interactive TVs, toasters, and more. Sun insiders called the Project Green, when WorldWideWeb was still on the drawing. The leader of the group is jamesgosling, a very outstanding programmer. He was born in 1957 and joined Sunmicrosystem in 1984, before working at an IBM Research Institute. He is the chief designer of the Sunnews window System. It is also the first developer to cosmacs the text editor of Emacs with the C implementation.

In the process of research and development, Gosling deep understanding of consumer electronics and workstation products in the development of philosophical differences: Consumer electronics products require high reliability, low cost, standardized, easy to use, users do not care about the CPU model, and do not appreciate the dedicated expensive RISC processor, They need to be built on a standard basis with a range of options, ranging from 8086 to 80586.

2, starting from C

To make the whole system independent of the platform, Gosling first begins with rewriting the C compiler. But Gosling in the process of rewriting that only C is unable to meet the needs, so in June 1991 began to prepare to develop a new language, then give it a name? Gosling looking out of the window, saw an old oak tree, and then built a directory called Oak, which is the predecessor of the Java language (later found that Oak is already a registered trademark of Sun Company Another language, was renamed to Java, the Pacific Coffee-rich island name).

Gosling in the beginning of writing Java, not limited to the expansion of the language mechanism itself, more attention to the language of the hardware and software environment running. He wants to build a system that runs in a huge, distributed, heterogeneous grid environment, and accomplishes communication and collaboration between electronic devices. Gosling in the design of Virtual machine code (VIRTUALMACHINECODE) mode, that is, the Java language compiled by the virtual machine, the virtual machine running on an interpreter, each operating system has an interpreter. As a result, Java becomes a platform-agnostic language. This has the same technical flavour as the Sunnews window system designed by Gosling. In news, the user interface is unified with PostScript descriptions, and different displays have different PostScript interpreters, which ensures good portability of the user interface.

Patricknaughton is also the technical backbone of sun, once the head of the OpenWindows project. When Naughton joined the team, the whole work progressed rapidly. After 17 months of fighting, the entire system was completed successfully. It is composed of an operating system, a language (Java), a user interface, a new hardware platform, three dedicated chips. Normally, such a project would take 75 people to dry for three years in sun company. After the project was completed, a presentation and identification was made within sun, and the audience responded by adopting new, very bold techniques in all aspects. Many visitors are very impressed with Java, especially with the attention of Sun's two leaders Scottmcnealy and Billjoy, but the future of Java is uncertain.

3. Turning point in the Java language

By the year 1994, WWW has developed in full swing. Gosling realizes that WWW needs a neutral browser, it does not rely on any hardware platform and software platform, it should be a high-real-time, reliable and secure, interactive function of the browser. So Gosling decided to develop a new web browser in Java.

The work was carried out by Naughton and Jonathanpayne, and the development of Webrunner was completed by the fall of 1994. Webrunner is the predecessor of HotJava, a prototype system that showcases the broad market outlook that Java can bring. Webrunner renamed to HotJava, and published on May 23, 1995, in the industry caused a great sensation, the status of Java has been affirmed. After a year of trial and improvement, the Java1.0 edition was finally released in early 1996.

Second, the impact of Java

Java has not been a long time, but has been accepted by the industry, IBM, Apple, DEC, Adobe, Silicongraphics, HP, Oracle, Toshiba, Netscap and Microsoft, and other large companies have purchased Java licenses. Microsoft has also added support for Java in its web browser version Explorer3.0.

In addition, many software developers have developed a number of Java-enabled software products. Such as: Borland's Java-based rapid application development environment latte; Machintosh-based Java development tools developed by Metrowerks Company and Naturalintelligence Company respectively Sun's Java development environment Javaworkshop;microsoft also developed a series of Java products. Database vendors such as Illustra,sybase,versant, Oracle are developing CGI (COMMONGATEWAYINTERFACE) support for HTML and Java. In a network-centric computing age, HTML and Java are not supported, which means that applications can be scoped to a homogeneous environment.

Intranet is becoming the best solution for enterprise Information System. Its advantages are shown in: cheap, easy to use and manage. Users regardless of the type of machine and operating system, the interface is a unified web browser, and databases, Web pages, Applications (Java-compiled applets) exist on the WWW server. Developers only need to maintain a version of the software, managers save for users to install, upgrade, training, users need only one operating system, an Internet browser is sufficient.

We can envision the future of computing, and the essence of each homepage is a multimedia application that is developed in Java. Java applications run on heterogeneous machines, heterogeneous operating systems, and even refrigerators, toasters, anti-theft electronic devices, using the Internet to connect all electronic devices to communicate information through TCP/IP. You can exchange messages between Java applications, or you can exchange programs (a Java applet applet). Maybe one day we can check the temperature of the refrigerator in the Netscape browser and send an e-mail to the Toast box.

The advent of Java is an important milestone in the exchange of computer information. In the time of single-machine, the exchange of variables between program processes is done by shared storage; In the network era, programs running on different host hosts are exchanged in unformatted messages (binary character streams) in network protocols, and the semantics of messages are maintained by both parties of the exchange program; In the Java ERA, A program process running on the network is exchanging small applications (applets). What is a small application? It is an object, consisting of a set of properties and methods, an executable entity, not only the state of the data, but also the operations defined on the data. In the future there may be representative (agent) Exchange, the agent has a certain degree of intelligence, that is, the more advanced stage of information exchange.

With the rise of the internet and the advent of Java, huge, bloated applications have begun to develop into miniaturization, with many "living" small applications (applets) on the Internet collaborating to complete the processing and delivery of information. Java will accelerate the trend of miniaturization and networking of application software. With the development of the Internet, software must be oriented to "the masses", rather than the "few" luxuries, but small profits and quick turnover will be an important feature of network application software. Distributed object Technology guarantees how much to use and how much to download.

Java, together with Internet,www, is changing the way applications are developed and used, all around the network, regardless of the platform. Many people think that the traditional information processing tools such as word,excel are bound to shrink, because they are the product of the single-machine era. The value of information is to use and share, the Internet and the Web are the quickest and cheapest way to use and share information, and Word will evolve into a web writing tool, and Excel will evolve into spreadsheets on the web.

Overview of the Java language