The JDK contains immutable collections, but no type `ImmutableCollection`. I explain why and claim that that’s never gonna change.
Transforming collections are a view onto another collection, making it appear to be of a different parametric type. This can be used to remove optionality from a collection or substitute ‘equals’ and ‘hashCode’.
If you write your own Java collections you will want to test your implementations. See how this works with Google’s Guava-Testlib.