Java: How to workaround the lack of Equatable interface?
- by java.is.for.desktop
Hello, everyone!
As far as I know, things such as SortedMap or SortedSet, use compareTo (rather than equals) on Comparable<?> types for checking equality (contains, containsKey).
But what if certain types are equatable by concept, but not comparable?
I have to declare a Comparator<?> and override the method int compareTo(T o1, To2). OK, I can return 0 for instances which are considered equal. But, for unqeual instances, what do I return when an order is not evident?
Is the approach of using SortedMap or SortedSet on equatable but (by concept) not comparable types good anyway?
Thank you!
EDIT:
I don't want to store things sorted, but would I use "usual" Map and Set, I couldn't "override" the equality-behavior.
EDIT 2:
Why I can't just override equals(...): I need to alter the equality-behavior of a foreign class. Can't edit it.
EDIT 3:
Just think of .NET: They have IEquatable interface which cat alter the equality-behavior without touching the comparable behavior.
