title: Java HashMap indexed on 2 keys
body: <p>I want to create a HashMap in java for users with preferences. This would be easy to do in a database, but unfortunately I can't use a database. What I need is a way to find a user by name in the HashMap, and to find all the users with a certain interest (e.g. golf). If I delete a user, then all their interests should be deleted. </p>
  
  <p>Anyone know a nice way to make this data structure?</p>