From http://scorcher7.tripod.ca/boggle.html

The java sources here (*.jad) are decompiled from the class files
using Jad from http://www.geocities.com/SiliconValley/Bridge/8617/jad.html

You should not assume that decompiled sources can be used to build a
working program; they are here only to allow you to study the methods
used in this code to help you write your own programs.