gistfile1.java

//Dog.java
public class Dog extends Animal {
    public final String mMyString = "bark";

    @Override
    public void doSomething() {
        System.out.print(mMyString);
    }
}

//Animal.java
public abstract class Animal {
    public abstract void doSomething();
}

//Cat.java
import java.util.ArrayList;
import java.util.List;


public class Cat extends Animal {
    Cat() {
        mMyList.add("Meow!");
        mMyList.add("Meow!!");
        mMyList.add("Meow!!!");
    }

    public List<String> mMyList = new ArrayList<String>();

    @Override
    public void doSomething() {
        for (String element : mMyList) {
            System.out.print(element);
        }
    }
}

//Host.java
import java.util.ArrayList;
import java.util.List;


public class Host {
    public static void main(String[] args) {
        new AnimalCaster().run();
    }

}

//AnimalCaster.java
import java.util.ArrayList;
import java.util.List;


public class AnimalCaster {
    private Animal mCat = new Cat();
    private Animal mDog = new Dog();
    private List<Animal> mAnimalList = new ArrayList<Animal>();

    AnimalCaster() {
        mAnimalList.add(mCat);
        mAnimalList.add(mDog);
    }

    public void run() {
        for (Animal a : mAnimalList) {
            System.out.print("\n-- begin --\n");
            a.doSomething();
        }
    }
}