Java commerce model?

Can anyone tell me (just curious) about the Java commerce model?

I had assumed one was just free to develop applications in Java and sell them to anyone, with no licences payable to Sun for use of the Java system. Is that the case, or am I wrong? If that *is* the case, you have to wonder how Sun make any money from Java at all? Especially when you look at things like NetBeans, which is a truly brilliant product, and must have cost millions to get it to where it is, yet (unlike Micrsosoft), they just give it away...

How do they make money from Java?

Just curious, thanks.