DrJava

DrJava is an open source, lightweight programming environment that can easily be pigeon-holed as an educational IDE for beginners. It does fill this role very well, through its simplicity and interactive interface. However, DrJava can also be quite a useful tool for more experienced programmers, with many powerful features that build upon its signature trait, the Interactions Pane.

DrJava's user interface is inspired by a similar educational environment used for the Scheme language, DrScheme (http://drscheme.org). As in DrScheme, DrJava's Interactions Pane allows users to experiment with their programs by evaluating expressions in a console-style window. For students, this is a great way to become comfortable with the Java language. For experienced programmers, the Interactions Pane can be used to experiment with new libraries, perform small tests, and track down problems. Even more significantly, recent versions of DrJava include a debugger closely tied to the Interactions Pane. Breakpoints can be used to suspend method calls in the Interactions Pane, which then switches to the context of the suspended method. This lets programmers easily view and modify the state of the program as if they were writing new lines in the method itself. This interactive debugger can also be used with DrJava's built-in support for running JUnit tests, making it easy to debug any unit test that fails. These abilities to interactively develop, test, and debug programs are remarkably useful even on quite large projects-- in fact, DrJava's own developers use DrJava almost exclusively to work on the IDE!

Apart from its Interactions Pane, DrJava has several other strengths that make it effective for both students and experienced developers. DrJava's small size and overall simplicity are advantages at any level, keeping it fast and easy to learn. Recently, DrJava has also gained the ability to generate Javadoc HTML files for packages or individual files, which provides quick and convenient access to APIs. Also, DrJava is ready for the future of the Java language, with support for using Sun's early access JSR014 compiler to write programs with generics. Even users of IBM's Eclipse IDE can take advantage of DrJava's Interactions Pane, since it is available as a plug-in to Eclipse.

All of these features combine to make DrJava an appealing IDE at any level of experience. DrJava continues to improve, as well, with upcoming support for pedagogic language levels and lightweight project support through the Ant scripting tool. Be sure to give it a try from http://drjava.org!

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