A simple question about class and extends??

Question

In inheritanve in java, every class must be in a file class diferents to run? Because when the class and extends are on the same page, the program don't run? Someone can help?

example: if i had super class animal and a subclass cat, both will run on the same page of IDE or one class must be in your onw page?

Answer 1

I don't understand your question.
Can you give an example?