I've done everything I know and found on the internet to open a .jar file, but nothing works. When I give 2 clicks it just does not open, it does not give a mistake, but it also does not open anything. I have already tried to run through the Windows Command Prompt, the following appears. "no main manifest attribute in Gym.jar", I already opened that folder in the manifest, I did change but it continues the same thing.
I also tested the file on another computer, gave it the same. I generated other .jar files and it also does not work. Generate these files by eclipse. I had already generated .jar files a few months ago and it worked fine, but now I do not know what else to do.
Inside in my file MANIFEST.MF has the following information: Manifest-Version: 1.0 Sealed: true.
