Need help at practice

Question

Hello there!
I need help on the practice exercise 46.2
I am stuck solving it for one week.
Today I decided I "cheat" by just writing the output in the main class and it worked.
But I want to solve it the right way.
Even with the help of the solved code I didn't figure it out.(It always says "no output ")
So can please some explain interfaces and abstract classes and send the solution for 46.2?
I would really appreciate it!

Answer 1

Could you please link your code?