Getting Started with Java Demography 2.0 

You have your choice in the ways that you can use JAVA Demography. You may use it directly from a web browser, such as Netscape (4.x or higher) or Internet Explorer (4.x or higher), you may use a special program designed to run applets (e.g., Apple's "Applet Runner"), or you may run it either in Windows or on a Mac as a stand-alone application. This flexibility is great; it is one of the main reasons that we chose to rewrite Demography in Java. There are, however, costs and benefits and minimal requirements associated with each option. In this section we provide a brief introduction to what you will need for each option, and we discuss the advantages and disadvantages of each approach.

NOTE: Check the Biology Software Lab web page for news on updates and upgrades, or sign up to be on the BSL listserve to keep informed via e-mail.

Using Java Demography with a Web Browser

Most recent versions of web browsers have the ability to run Java applets. Unfortunately, we have found it extremely difficult to get Demography to run properly using the many different Java interpreters that are built in to current web browsers.

To circumvent these problems, we have chosen to focus on compatibility with Java plug-ins. Plug-ins are available for both Macintoshes and PC's, as well as most other machines. If you have any difficulty running Demography from within your web browser, we strongly urge you to install the appropriate Java plug-in and try again!

In addition, we have made extensive use of a set of interface tools produced by Sun Microsystems called the Java Foundation Classes, aka "Swing". These tools are built into Java 2.0. If you are using Java 1.1.x, however, you will also need to download and install the Swing components. NOTE: This version of Demography requires a Java 1.1 or Java 2.0 interpreter. It will not work with Java 1.0.

For Windows^TM and Unix^TM users :

• Step 1. Installing a Java Plug-In for your Web Browser

Download and install the Java plug-in produced by Sun Microsystems

• Step 2- Configuring Your Web Browser

Set the preferences for your web browser so that Java and Javascript are enabled, and make sure that your browser is set to use the Java plug-in rather than it's own Java interpretor.

For Macintosh^TM users:

(Software Installation on the Mac will require about 40 megs of hard disk space)

• Step 1- Installing the MacOS Runtime for Java (MRJ)

You should make sure that you have the most recent version of the MacOS Runtime for Java (MRJ). At the time this is being written, the current version (9/99) is MRJ 2.1.4. You should at least have version 2.1. Download the MRJ from Apple, and follow the installation instructions. If you are using an earlier version of the MRJ, you should at least make sure that your version is compatible with the latest version of Swing (1.1.1).

• Step 2- Installing the Java Foundation Classes

Download and install the most recent version of Swing from Sun Microsystems. Place all the ".jar " files located in the Swing- 1.1.1 folder in the following location inside your System Folder -- System Folder:Extensions:MRJ Libraries:MRJClasses:

• Step 3- Installing a Java Plug-In for your Web Browser

Applications such as Microsoft Internet Explorer and the Apple Applet Runner work with MRJ. (Note that for Internet Explorer, you may have to change preference so that it uses the MRJ rather than the Microsoft Virtual Machine). Unfortunately this is not true for current versions of Netscape Communicator and Navigator (up to and including at least 4.5). These use their own internal Java virtual machine which is not yet compatible with the newest Java releases. Apple and Netscape are working together to develop a future version of Netscapeís browser that will use MRJ. That may take a while! In the meantime, you can download a plug-in for Netscape (beta version) that allows Netscape to use the current MRJ. Make sure the files "MRJ Plugin" and "MRJPlugin.jar" are placed in your browser's "Plug-Ins" folder.

Please note that the Mac Java plug-in will not work with versions of Netscape below 4.0.

• Step 4- Configuring Your Web Browser

For Netscape 4.x: Choose Preferences from the "Edit" Menu".Click on "Advanced". Make sure that Java and Javascript are enabled. Click on "Applications". Make sure that "Embedded Java Applet" appears under your list of applications and that MRJ Java Plugin appears next to it in the "Handled by" column (see two figures below

For Internet Explorer 4.x: Click on "Preferences" on the tool bar. Select "Java" from the list on the right of the dialog box (see below). Make sure that Java is enabled, that Apple MRJ is chosen as the Java virtual machine, and that the swingall.jar and mac.jar files are listed under "Class Paths".

Much of what was said above also pertains to using "applet runners" or "applet viewers". These programs, however, are designed to use the Java Virtual Machine that is installed into your operating system. The Java plug-in is not required.

For Windows and Unix users :

For Macintosh users:

(Software Installation on the Mac will require about 40 megs of hard disk space)

• Step 1- Installing the MacOS Runtime for Java (MRJ)

You should make sure that you have the most recent version of the MacOS Runtime for Java (MRJ). At the time this is being written, the current version (9/99) is MRJ 2.1.4. You should at least have version 2.1. Download the MRJ from Apple, and follow the installation instructions. If you are using an earlier version of the MRJ, you should at least make sure that your version is compatible with the latest version of Swing (1.1.1).

Applet Runner is automatically included in your MRJ installation package.

• Step 2- Installing the Java Foundation Classes

Download and install the most recent version of Swing from Sun Microsystems. Place all the ".jar " files located in the Swing- 1.1.1 folder in the following location inside your System Folder -- System Folder:Extensions:MRJ Libraries:MRJClasses:

Stand-alone versions are not available at this time! This should be coming in the very near future.

Which Method Should I Use?

The main advantage of using a web browser is that the applet can be embedded in a group of web pages that include instructions and other curricular materials. This manual is an example of that. On the other hand, web browsers can be memory-intensive. If you are using an older computer with limited memory, you might choose to use an applet viewer or the stand-alone version.

One of the main advantages of the stand-alone version is the ease of printing, and opening and saving files. For Windows and Unix users this is less of a problem, because these features are accessible from the Java applet provided that you have obtained a "key". At the moment, though, these features are not available for Applets on the Mac.

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