About Question enthuware.ocpjp.v11.2.3352 :

[get4gopi]

The question itself wrong -

Which of the following are valid implementations of java.util.Comparable?

Comparable interface is in java.lang package not in java.util package. Only the comparator interface is in java.util package.

https://docs.oracle.com/en/java/javase/ ... to,sort%20(and%20Arrays.&text=Note%20that%20null%20is%20not,of%20any%20class%2C%20and%20e.

[admin]

You are right. Fixed.
thank you for your feedback!