Verify that you can start your application like that:
java -cp myjarfile.jar snake.Controller
I just read when I double click on it – this sounds like a configuration issue with your operating system. You’re double-clicking the file on a windows explorer window? Try to run it from a console/terminal with the command
java -jar myjarfile.jar
Further Reading
- Running JAR file on Windows
The manifest has to end with a new line. Please check your file, a missing new line will cause trouble.