I am searching for some Java code or library that allows me to solve
systems of linear (or non-linear) inequalities. I have found some code
(e.g., Cassowary), but it is thought only to find one solution, instead of
the set of all possible solutions.

For example, for the system:

2x>=6
x>0

it would find as a solution x=3, instead of the set of solutions x>=3.

Thanks in advance for any suggestion or link that can help me with my
search. I'm kind of lost among so many links about linear programming.