How to programmatically test if assertions are enabled?

Question

One of the correct answers from OCP Java SE 6 Programmer Practice Exams is:

You can programmatically test wheather assertions have been enabled without throwing an AssertionError.

How can I do that?

Answer 1

I use this

boolean assertOn = false;
// *assigns* true if assertions are on.
assert assertOn = true; 

I am not sure this is the "official" way.