Without the use of collections or arrays? That is going to be very hard then. It's like asking for an alternative to wheels on your car, but without using round things...
You could in theory create a Linked List of Linked Lists and use that as a hash map (using each element in the larger list as a bucket), but that would probably have poor performance and I wouldn't even try myself.
So when you said "without use of Collections" you didn't actually mean not using the Collections API -the Commons Collections library makes extensive use of that- but rather you were looking for a class outside of the java[x] packages. That still leaves open the question of "why?".