Hello! My Minecraft won't open as a jar file. When I download the server jar file, it automatically turns in minecraft_server.1.11.2, except it isn't a jar. It makes a folder with a zipper and puts this in it: assets, com, is, it, Javan, net, org, a.class, aa.calss...etc.
sounds like you have your compression program assigned to the .jar file type don't panic that should not make any difference to your startup script getting your server running unless you try to run it by double clicking the jar itself which is not the best way to start a server.
so use a startup script and you will be fine
and you can always deassign .jar from your compression software as a safe guard
The best way is to run it from a batch file, as it allows for easier customization of Java parameters. You can start it like williyao shown above in the alternate solution. I would only add that instead of just typing java etc you make a batch file so you don't have to type it every time. If you run into memory problems, you may also want to specify heap size switches. How much RAM do you have?