When debugging an applet, you must begin by debugging the sun.applet.AppletViewer class. After you have begun debugging this class, you can open the source for any class which is part of your applet and set breakpoints.
You can start to debug an applet by following these steps:
idebug -qlang=java sun.applet.AppletViewer <applet_location>
Where <applet_location> is one of the following:
We recommend that you set a breakpoint on the init() or start() methods since these are the first methods that are called by the applet viewer.
Once you have set this breakpoint you can debug your applet as you would debug a Java application.