- object language defined by SUN
- published into 95
- intended for the origin for the embedded devices (household, settop boxes, cars...)
- platform independent language
- adopted by the Web community for secure and cross-platform way for code: applets in the Web pages...
- principles of Java
- concept of abstract machine based on an intermediate code called J-code
- on each platform a program called " Java Virtual Machine " (JVM) interprets and execute the J-code downloaded through the network
- advantages of Java
- cross-platform: soon even on smart card!
- made safe: an inspector of J-code makes sure that the Java programs respect the limitations of security (not virus known to date in Java)
- supported per many navigators, even if the last versions of Java are not always integrated...
- HTML file of description of the Web page indicates that a rectangular zone will be controlled by a Java program whose code is placed on the Web in the form of class files or of compressed jar archive
- during the loading of the page in the navigator, the Java code is transmitted to allow the display of the zone by the applet. This code is interpreted by the virtual machine Java which must be present beforehand in the computer of the Net surfer. This one is installed out of standard with the modern systems, but must from time to time be updated (see here for MacOS and there for Windows)
- Java is a computer language like the others: a complete program can be written in Java. It will be executed on all the systems having an interpreter of J-code = a virtual machine Java
- a Java program launches out apart from any navigator, but Java makes it possible to facilitate the accesses to the network, which makes it possible to consider programs remotely cooperating between them or searching resources on the network.