9.5.3. Superclass Arrays and ArrayLists Unit Test

[DebMDuke]

The last unit test, "Checking that code contains petList.add(new Cat())" fails unless a call to the constructor of Cat is passed null.
Specifically,
import java.util.; // for ArrayList

public class Pet
{
private String name;
private String type;

 public Pet(String n, String t)
 {
    name = n;
    type = t;
 }
 public String toString()
 {
    return name + " is a " + type;
 }

 public static void main(String[] args)
 {
     ArrayList<Pet> petList = new ArrayList<Pet>();
     petList.add(new Pet("Sammy","hamster"));
     petList.add(new Dog("Fido"));
     petList.add(new Cat("Fluffy"));
     petList.add(new Cat("?"));
     petList.add(new Cat(null));                   // passes with this statement; fails otherwise
     
     // This loop will work for all subclasses of Pet
     for(Pet p : petList)
     {
        System.out.println(p);
     }
 }

}
class Dog extends Pet
{
public Dog(String n)
{
super(n, "dog");
}
}

class Cat extends Pet
{
public Cat(String n)
{
super(n, "cat");
}
}

[bhoffman0]

Thanks! I've fixed this and it will be live on 8/8.