Enthuware

I think the good answer should be:

It is an abstract class that has only one abstract method ...

and not

It is an interface that has only one method ...

As it is written in explanation:"This interface has exactly one abstract method named test"

And in official documentation (http://docs.oracle.com/javase/8/docs/ap ... icate.html) java.util.function.Predicate has more than one method (and, isEqual, negate, or)

You are partially right. It does have more than one method (although only one abstract method). However, it is an interface not an abstract class.
Fixed.
thank you for your feedback!
Paul.