Using the Debugger - touniez/comp402doc GitHub Wiki
To use DrJava's debugger, select the "Debug Mode" command from the Debugger menu. An informational panel will be displayed between the Definitions Pane and the Interactions Pane, and several menu items in the Debugger menu will become enabled.
A Note on Modifying Files
When using the debugger, it is essential to remember that any modifications to source files will not be reflected in the behavior of the Interactions Pane or the debugger until the classes are recompiled. Changing a source file while the debugger is running is not recommended, since lines which are highlighted by the debugger may no longer correspond to the lines in the running class file. To help notify you of this danger, DrJava displays a warning message in the Debug Panel if the current document is out of sync with its class file.
Because the debugger depends on the classes used in the Interactions Pane, the debugger is automatically reset each time any files are compiled, or when the Interactions Pane is reset.