(Solved): CSE205 Quiz 5: Inheritance and Polymorphism ...

CSE205

Quiz 5: Inheritance and Polymorphism 

Question 1

1 / 1 pts

T/F? - Private properties are not inherited into a child class.ou Answered

•   True
•   False

Question 2

1 / 1 pts

Sometimes inheritance is unnecessary and you should just create a well written Interface instead.  

Note: we're talking of Interfaces like Comparable and such, not the "public interface" Correct!

•   True
•   False

Question 3

1 / 1 pts

What is true about the protected keyword in terms of inheritance?t!

•  Protected items are accessible within the scope of child classes but inaccessible outside to outside scope.

Correct!

•  If you don't use protected, you have to rely on the public interface of the parent class to access/use parent functionality

•   Protected members of a class have extra security built in via the compiler.

Correct!

•  Shockingly ... protected properties and methods are accessible within the scope of anything that shares the package of the class.

This is actually true ... free point ... I forgot to mention this in lecture because I often don't use packages in my sample code for the sake of time.  This is a Java feature.

•   Protected members are inaccessible in child classes, we use private to make them accessible.

Question 4

1 / 1 pts

Which of these are an example of polymorphism in the real-world?

• Automobiles

Different cars, while having the same interface can have very different implementations

•   Different colors of houses!
•  Smart phones 
•  Radio stations that play different music/formats

This would actually be one class ... only the content really changes.

•   The streets in a city 

Question 5

1 / 1 pts

If I want a parent that creates a consistent, reliable set of methods for an inheritance hierarchy, which technique should I use?

•   Create and use an Interface
•   Keep parent methods private so that children must provide their own public interface
•   Provide multiple definitions of the same method to customize functionalityCorrect!
•   Create an abstract base class with several methods that are abstract

Question 6

1 / 1 pts

In Java, which keyword do we use to create a method that has no body that exists only to be overridden by a child?

•   virtual
•   finalCorrect!
•   abstract 
•   None of these 
•   interface

Question 7

1 / 1 pts

Given a class Animal has a child Cat and a child BigCat.  Cat has a child class Tabby and BigCat has a child class Tiger.

Given the code:

Animal animal;

Cat kitty = new Cat();

BigCat big = new BigCat();

Tiger tig = new Tiger();

Tabby tab = new Tabby();

Will this code produce an error?

kitty = null;

•   yesorrect!
•   no 

Question 8

1 / 1 pts

Given a class Animal has a child Cat and a child BigCat.  Cat has a child class Tabby and BigCat has a child class Tiger.

Given the code:

Animal animal;

Cat kitty = new Cat();

BigCat big = new BigCat();

Tiger tig = new Tiger();

Tabby tab = new Tabby();

Will this code produce an error?

animal = big;orrect!

•   no 
•   yes

Question 9

1 / 1 pts

Given a class Animal has a child Cat and a child BigCat.  Cat has a child class Tabby and BigCat has a child class Tiger.

Given the code:

Will this code produce an error?

big = tig;

•   yesCorrect!
•   no

Question 10

1 / 1 pts

Given this code:

Animal myDog = new Dog(“Spot”);

myDog.speak();

What do we know about the Dog class and the Animal class?

•   Animal is derived from Dogorrect!
•   Dog is derived from Animal and Speak() is a method from the parent class that Dog over-rides 
•   We can tell nothing from this particular code.  We don't see any definitions.
•   Dog is actually an Interface for animal allowing an Animal to become a Dog.

Question 11

1 / 1 pts

Given a class Animal has a child Cat and a child BigCat.  Cat has a child class Tabby and BigCat has a child class Tiger.

Given the code:

Will this code produce an error?

big = tab;

Correct!

•   yes 
•   no