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

Very interesting question. As far as I understand your problem is duplicate elements.

I think that if o1.equals(o2) their hash codes might be equal too. It depends on the implementation of hashCode() in your Foo class. So, I'd suggest you to use System.identityHashCode(x) instead.