Android Firebase - 如何进行查询

I'm doing saving post feature now. I want display all saved post in one activity. I have made an activity where is RecyclerView in which I store all of posts and I have made made PostRow activity already. I have this databse: . I want to get all post which user has saved and i dont know how to get them from database. I have made PostAdapter: I'm doing saving post feature now. I want displ