Java data structures example

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/**
 * Animal.java
 *   Represents a single Animal.
 */
public class Animal
{
   private String name;
 
   /* constructor - Sets up the Animal with a name 
    * @param animalName String
    */
   public Animal(String animalName)
   {    
      name = animalName;
   }
 
 
   /* toString - Returns this Animal's name as a string 
    * @return name String
    */
   public String toString()
   {
      return name;
   }
}
 
 
 
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/**
 *  AnimalList.java
 *    Represents a collection of Animals.
 */
import Animal;
 
public class AnimalList
{
   private AnimalNode list;
 
   /* constructor - Sets up an initially empty list of Animals */
   AnimalList()
   {
      list = null;
   }
 
   /* add - Creates new AnimalNode object, adds it to end of the linked list 
    * @param animalName Animal  the common name of the animal
    */
   public void add(Animal animalName)
   {
      AnimalNode node = new AnimalNode(animalName);
      AnimalNode current;
 
      if (list == null) 
      {
         list = node;
      }
      else
      {
         current = list;
         while (current.next != null)
            current = current.next;
         current.next = node;
      }
   }
 
   /* toString - returns this list of Animals as a string 
    * @return result String  outputs animal names line-by-line
    */
   public String toString ()
   {
      String result = "";
 
      AnimalNode current = list;
 
      while (current != null)
      {
         result += current.Animal.toString() + "\n";
         current = current.next;
      }
 
      return result;
   }
 
  /**
   * AnimalNode
   *   An inner class that represents a node in the Animal list. The
   *   public variables are accessed by the AnimalList class.
   */
   private class AnimalNode
   {
      public Animal Animal;
      public AnimalNode next;
 
      /* constructor - Sets up the node */
      public AnimalNode (Animal theAnimal)
      {
         Animal = theAnimal;
         next = null;
      }
   }
}
 
 
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/**
 *  Zoo.java
 *   Driver to exercise the AnimalList collection. There could
 *   be many other types of collections of animals, such as a 
 *   WildernessPreserve, Aquarium, IndiginousRegion, SpeciesGroup, etc
 */
import AnimalList;
import Animal;
 
public class Zoo
{
   String zooName = "JAVA"; //name of zoo with default (displayed in output)
 
   /* 
    * constructor
    *   sets up a zoo with a given name
    * @param theZooName String  name of the zoo
    */
   public Zoo(String theZooName) {
     zooName = theZooName;
   }
 
  /*
   *  Creates an AnimalList object, adds several animals to the list,
   *  then prints them as a representation of a Zoo.
   */
   public static void main (String[] args)
   {    
      AnimalList animals = new AnimalList();
 
     //adding all my favorite animals to the Zoo
        animals.add (new Animal("Elephant"));      
        animals.add (new Animal("Tiger"));
        animals.add (new Animal("Cheetah"));
        animals.add (new Animal("Lion"));
        animals.add (new Animal("Hawk"));
        animals.add (new Animal("Eagle"));
        animals.add (new Animal("Gorilla"));
        animals.add (new Animal("Chimpanzee"));
        animals.add (new Animal("Spider Monkey"));
        animals.add (new Animal("Snow Owl"));
        animals.add (new Animal("Otter"));
        animals.add (new Animal("Shark"));
        animals.add (new Animal("Dolphin"));
        animals.add (new Animal("Killer Whale"));
 
      System.out.print("'" + zooName + "' Zoo. ");
      System.out.println("Proud home to the following animals:");
      System.out.println(animals); 
   }
}