TDD-AnimalFactory-BlueJ/AnimalWarehouse.java

import java.util.ArrayList;

/**
 * @author leon on 4/19/18.
 * this class is an abstraction of how Animals are stored and retrieved
 */
class AnimalWarehouse<AnimalType extends Animal> {
    private volatile ArrayList<AnimalType> list = new ArrayList<>();

    public void add(AnimalType animal) {
        list.add(animal);
    }

    public AnimalType getAnimalById(int id) {
        for(AnimalType animal : list) {
            if(animal.getId() == id) {
                return animal;
            }
        }
        return null;
    }

    public void removeAnimal(Animal animal) {
        list.remove(animal);
    }

    public void removeAnimalById(int id) {
        removeAnimal(getAnimalById(id));
    }

    public Integer getNumberOfAnimals() {
        return list.size();
    }

    public void clear() {
        list.clear();
    }
}