AnimalArray.java

// Animal.java

public class Animal {
    protected String type;

    public Animal() {
        type = "Unknown";
    }

    public String getType() {
        return type;
    }
}


// Cat.java

public class Cat extends Animal {

    public Cat() {
        type = "Cat";
    }

}

// Dog.java

public class Dog extends Animal {

    public Dog() {
        type = "Dog";
    }

}


// AnimalArray.java

import java.util.ArrayList;

public class AnimalArray {

    public static void main(String[] args) {

        Cat cat = new Cat();
        Dog dog = new Dog();

        ArrayList<Animal> animalList = new ArrayList<Animal>();

        animalList.add(cat);
        animalList.add(dog);

        for (Animal animal : animalList) {
            System.out.println( animal.getType() );
        }
    }
}


// Output
//
// Cat
// Dog