How do I make the method return type generic?

Question

Consider this example (typical in OOP books):

I have an Animal class, where each Animal can have many friends.
And subclasses like

Answer 1

This question is very similar to Item 29 in Effective Java - "Consider typesafe heterogeneous containers." Laz's answer is the closest to Bloch's solution. However, both put and get should use the Class literal for safety. The signatures would become:

public  void addFriend(String name, Class type, T animal);
public  T callFriend(String name, Class type);

Inside both methods you should check that the parameters are sane. See Effective Java and the Class javadoc for more info.