Java Platform Debugger Architecture - Example JDI Applications

From the Java SE Downloads page, you can download JDK and JavaFX demos and examples. When you download and unzip this package, the demo/jpda directory contains source code and documentation for three applications written using the Java Debug Interface (JDI) of the Java Platform Debugger Architecture (JPDA). They are provided as educational tools and as starting points for debugger development.

In increasing order of complexity:

Trace displays traces of program execution. It is very simple (less than 600 lines) yet uses most of the basic JDI functionality. It is a good starting point.
Jdb is the command line debugger.
Javadt is the beginnings of a GUI debugger.

Trace is in the trace directory. Jdb and Javadt share a package, and are in the debug directory.

Required Set-up

Your classpath must include the JDI Library code, which is in lib/tools.jar directory of the JDK. (Note that tools.jar is not in the Java Runtime Environment; it is only in the JDK.) This is needed for both compiling the example code and executing it. For information on how to set the classpath, see the JDK Tools and Utilities documentation.