What program was used to create these games from the site http://dedomil.net/?

[lorenzo]

What is the program that was used to create these java games from this site? I downloaded many games in jar format and then I decompiled the classes to java format codes with JD-GUI and then I tried to compile with eclipse or WTK but they show me 100 errors and warnings and hence they do not compile back to class I only I wanted to compile these classes to see how these resource files that are included in the jar file are created in the WTK res folder so how can I compile these classes without giving 100 errors and warnings? some help?