DrJava

DrJava will be used in class to demonstrate programming in Java. In addition, you should download DrJava onto your computer and use it heavily in practicing programming in Java.

DrJava was developed by Professor Corky Cartwright at Rice University.

Both DrJava and Codewarrior are installed on CIT's computers.

Table of contents

Need for a virtual machine

downloading DrJava

finding tools.jar

running DrJava

documentation on using DrJava

You need a Java virtual machine

DrJava requires a Java 2 v1.3 (or later) virtual machine and software development kit (SDK). If you are using a PC running a version of Windows, chances are that you don't have it yet (although a recent court ruling may change that in the future).

If you have a Macintosh with Mac OS X, you almost certainly have the Java SDK installed already, and you don't have to download the SDK.

One virtual machine/SDK is Sun's J2SE SDK --follow that link and select "DOWNLOAD" from the right-hand column that appears. Warning: this is a big download! If you want to download the Java API specifications, look at the very bottom of that page for "J2SE v 1.4.1 Documentation".

Downloading DrJava

Download DrJava (by clicking the link). The page will show you several versions of DrJava. Get the latest, which at the time of this writing is drjava-stable-20030822.jar. Note that DrJava won't run unless you have a Java 2 v1.3 (or later) virtual machine already installed.

Warning: you may get a dialog saying something about a "JAR archive security check". If you do, just right-click on the DrJava download link and select "Save Link As" (or the equivalent in your browser).

We know that all this setup can be annoying, but you have to do it only once!

A common DrJava problem: finding tools.jar

Question: I downloaded Sun's J2SE SDK and DrJava. When it came to actually running DrJava, the following window kept popping up even though somehow DrJava still managed to run without me finding the file --what should I do?:

Compiler not found. The file you chose did not appear to contain the compiler. Would you like to pick again? The compiler is generally located in 'tools.jar', in 'lib' subdirectory under your JDK installation director. (If you say 'No', DrJava will be unable to compile programs.)

Answer: First, make sure you installed the Java SDK, not the JRE. (See above.)

Now you need to find a file called "tools.jar". If you're using Windows, then when you installed the SDK, you probably put it in "Program Files". The name of the Java folder is probably something like "j2sdk1.4.0_01"; look inside that for a directory called "lib", and inside "lib" look for "tools.jar".

Running DrJava

There are several ways to run DrJava:

From the command line, you can type java -jar drjava-stable-20030822.jar
On many platforms, you can simply double-click the jar file to start DrJava.
On OS X, you can download drjava-stable-20030822-osx from the download page. You can then run DrJava as a normal application.

Documentation --how to use DrJava

The demos given in class and in the demo sessions should help, if you take notes. However, here is documention on using DrJava on the web. In addition, Appendix I of the text contains information on using DrJava.