Comparator and equals()

Question

Suppose I need TreeSet with elements sorted with some domain logic. By this logic it doesn\'t matter order of some elements that doesn\'t equal so compare metho

Answer 1

If you have no specific expected ordering for any two given elements, but still want to consider them un-equal, then you have to return some specified ordering anyway.

As others have posted, hashCode() isn't a good candidate, because the hashCode() values of both elements can easily be equal. System.identityHashCode() might be a better choice, but still isn't perfect, as even identityHashCode() doesn't guarantee unique values either

The Guava arbitrary() Ordering implements a Comparator using System.identityHashCode().