Java: Implementing a Unsigned 128bit Integer

Question

first off I should ask:
Does anyone knows of a current implementation 128b UINT for Java?

I need something to hold natural cardinal

Answer 1

I would use 32 bit integers as the representation, because you need a bigger type (long) to get the extra precision for the carry bit, overflow detection and multiplication. Think of a 32 bit integer as a digit and apply the algorithms from primary school.