Java, Strategy Pattern, Generics and return type

Question

I'm implementing the Strategy Pattern:

public interface Stuff<T> {
  T getStuff();
}

public class IntegerStuff implements Stuff<Integer> {
  public Integer getStuff() { .. }
}

public class StringStuff implements Stuff<String> {
   public String getStuff() { .. }
}

Now, I want to use a "Context" to set the strategy and execute the strategy method:

public class Context() {
   private Stuff stuff;
   public setStrategy(Stuff stuff) { this.stuff = stuff; }

   public Object doStuff() { // ARGH!
      return stuff.getStuff()
   }
}

How can I use generic, so that the type of the doStuff() method on the Context class, can be of the same type as the used strategy?

Answer 1

You would want to parameterize Context as well:

public class Context<T> {
   private Stuff<T> stuff;
   public setStrategy(Stuff<T> stuff) { this.stuff = stuff; }

   public T doStuff() { // ARGH!
      return stuff.getStuff()
   }
}