exactly what is a implementation compare ? also @override ?

Comparator<Type> is a Java interface, interfaces are basically a way of exposing some of the functionality of one class to another without you having to worry about all the implementation details.

But, because the Comparator interface already has it's own version of the method compare() and you want to make a customized version of that method for your own class, you use an annotation that tells the java compiler "nevermind that version of the method, use mine."

That's where the @Override annotation comes in.

Thank you so much for that answer. I thought we were overriding because it was necessary to override to use the method. But we're overriding to manipulate the method how we want.