Whats the error coders,I am new to this

Question

https://code.sololearn.com/c29JcXTKo51J/?ref=app

Answer 1

because Demo is inner (non-static) class
on create object you have to first specify object where demo class is

Demo ref = ref1.new Demo();

edit: code was then changed to 3 separated classes

Answer 2

You're inheriting and nesting the class at the same time?

Answer 3

Thanks zemiak

Answer 4

Nick i forgot to create class for main