The paper introduces the Java programming language, its advantages and disadvantages, and its characteristics for developing interactive instructional applications on the Web. The interactive and computational capabilities of Java are demonstrated through a simple matrix assembly Java applet. With this applet, students assemble element equations into the global equations for structural analysis using the bar element. The matrix assembly applet features a graphical user-friendly interface, on-line help and interactive feedback.

Most popular web browsers, such as Microsoft Internet Explorer (version 3 and above) and Netscape (up to version 4) have built-in support for early versions of Java. This is sufficient for viewing most existing applets and should work without requiring any software to be installed, though you may find that some applets do not run properly on very old browsers as they come with poorer support for Java. The Sun Java Plug-in allows browsers to display applets which have been authored to use modern Java features not compatible with the older versions of Java included with popular browsers.

To view such applets, you will need to install the Java plug-in on your computer. This is part of the Java 2 Run-time Environment (known as the J2RE or JRE) which can be freely downloaded . In most cases, you will be automatically guided through the installation when you try to view an applet that needs a plug-in. However, some applets on the web are not coded in such a way as to make this happen, so if you find that some applets report error messages or just don't work correctly then it may be an idea to try installing the plug-in first and see if that helps. Installing the plug-in first is also sensible as it guarantees that you will get the most recent version of the plug-in supported by your computer.