Specializing method arguments in subclasses in Java

Question

Consider the following situation:

public abstract class AnimalFeed{
}
public class FishFeed extends AnimalFeed{
}
public class BirdFeed extends AnimalFeed{
}         


        

Answer 1

You'd need to add a type variable to the class:

public abstract class Animal {
  public abstract void eat(F somethingToEat);
}

Then you can declare your subclasses as wanting a particular type of AnimalFeed:

public class Bird extends Animal {
  public void eat(BirdFeed somethingToEat) {}
}

public class Fish extends Animal {
  public void eat(FishFeed somethingToEat) {}
}