Make Collection and arrays more compatible
and more easily to use together.
Add the following methods to Collection:
addAll(<? extends E> array)
containsAll(<? extends E> array)
removeAll(<? extends E> array)
retainAll(<? extends E> array)
(Or maybe better to a new interface, so that existing code won't be broken, and have the library classes that implement Collection implement the new interface).
And if this is possible (I never understood why it is not working this way and why one has to supply an array as an argument):
change Object toArray() to E toArray() and make it work like T toArray(T a)