Why am I getting "no main manifest attribute, in main.jar" error message

Question

I started learning Kotlin about 18 months ago and, having tried various compilers, found GDB. It does everything I need and has been fine for the past 9 months I have been using it. For reasons unknown it has now started throwing up an error message when I load and attempt to run saved files. The message reads "no main manifest attribute, in main.jar". Until recently I had no issue whatsoever. I could write code with Kotlin, run it, save it and run it again without problems. When I start GDB now it starts with the usual "Hello World" and will run it but if I save that, load it again and attempt run it I get the same message. I would hate the idea of having to give up with GDB, it does all I need and is about the only compiler to recognise Kotlin's readln() statement.

Any assistance form other users will be gratefully received.

Regards Ged

Answer 1

I am not a Java developer, but when I played around with some toy projects, I remember I couldn't use packages in OnlineGDB. If I did not put my code into a package, it worked. Maybe you have the same problem.

Please, share your code for analysis.