Because you can use applets interchangeably with panels they're easy to test and debug. Debugging is even easier if the applet runs as a standalone application rather than within a browser. Let's run one from the interactive interpreter.
Import Applet, List, and Frame.
>>> from java.applet import Applet >>> from java.awt import List, Frame
Create an instance of Applet and List; add the List instance to the applet instance.
>>> applet = Applet() >>> list = List() >>> applet.add(list) java.awt.List[list0,0,0,0x0,invalid,selected=null]
Create an instance of Frame; add applet to it.
>>> frame = Frame("Frame that contains the Applet") >>> frame.add(applet) java.applet.Applet[panel0,0,0,0x0,invalid,layout=java.awt.FlowLayout] ...