I don't want a classmate to use my stuff
Why won't you let them use your stuff?
He once used my shampoo without asking. He'll just abuse it.
You should share with your classmate. It was probably just a one-time circumstance that he used your shampoo. Maybe he really needed it.
You are not even understanding. It's not because he used it. It's because he's a homeless.
That's an even worse reason not to share. Maybe they needed it for hygiene.