Advertisements I have followed the directions on the Kmttg wiki for Windows. I have Java 1.8.0_221. I have done the following: First determine full path to your Java installation javaw.exe file. Then start a cmd window as administrator and type: assoc .jar=jarfile ftype jarfile="C:\Program Files (x86)\Java\jre1.8.0_45\bin\javaw.exe" -jar "%1" %* (Of course replace path to javaw.exe above with your java installation path.) And the Jarfile won't open with Java. Just a blank black box. Any help would be greatly appreciated.