Basic Java Concepts

• Java is a full computer language. It is roughly comparable to C++ (more than to any other common programming language), with some simplifications and improvements.

• Java is interpreted. A web browser, applet viewer or java interpreter functions as a "virtual machine." Java is not Javascript.

• Source code (*.java) is compiled into "virtual machine" code (*.class). The .class files are compressed, binary files that are interpreted.

• Because Java is interpreted, it is a cross-platform language. The same Java program will run on any system which implements the virtual machine. At a minimum (since this list is already known to be outdated), Netscape provides Java support for Windows 95 and NT, Macintosh 7.5, Solaris, Irix, HP-UX, and linux. IBM itself reportedly supports Java under OS/2, AIX and Win 3.1. Oracle PowerBrowser 1.5 supports Java. And so on.

• Because Java is interpreted, it is slow.

• Programs can be run as stand alone programs, or they can be "applets" embedded in web pages. Applets have very little access to the system resources on the client machine. As stand alone programs, Java programs have the same access as other programs.