Question about telling if someone is gay

I am a male senior in high school. Pretty sure i am bi or gay but i am still a virgin so i don't know for sure. Also i have never told anyone about probably being gay. I have a small group of friends. Recently i started developing really strong feelings for one of my friends. He never really talks about girls and has not had a girlfriend since around 5th grade. I was wanting to know if there is any way to tell if he is in the closet. Any sure way to tell if he is or probably is without revealing myself? I realize that he is probably straight but i like him a lot and if there is any way to find out if he isn't that would be really helpful.