Mac OS El Capitan never opens .jar files

Question

Every time I try to save a.jar file for my programming course and it doesn't open, and yes I save the META.MF whit the correct path, I even stop making them on the Terminal and use Net Beans but same problem Error: Could not find or load main class a3t8e1.A3T8e1 maybe I need to download something else.

I search on the internet and download the jar launcher but nothing better.

this is the .jar unpacked

Answer 1

Please try to right click the .jar file and click the Get Info . Under the Open with , select the Jar Launcher.app . After that, try to reopen your related .jar file.