examples of user-space and kernel-space

I was asked :

• of examples of user-space-threaded-only systems, kernel-space-threaded-only systems.
• whether Native POSIX Thread Library is considered part of user-space or kernel-space.
• and if Java threading is done in user-space.

there's a huge amount of information about all these topics, but there doesn't seem to be a direct answer to those specific questions. I hope you could help me.