Card      c;
Valentine v;
Birthday  b;
Holiday   h

A good answer might be:

  • c = new Valentine("Debby", 8); //OK
  • b = new Valentine("Elroy", 3); //WRONG
  • v = new Valentine("Fiona", 3); //OK
  • h = new Birthday ("Greg", 35); //WRONG

Another Hierarchy

Here is a picture of another hierarchy: There are no abstract classes in this hierarchy, so each class can be instantiated. As seen previously, the following is OK: 

parentReference = childReference
A parent reference variable can hold a reference to an object of one of its child types (or a reference to one of their child types, and so on.) However, the opposite direction 
// don't do this
childReference = parentReference
can not be done, unless the parentReference actually refers to a child object (this is rare.)


Here are some variables: 

Rodent     rod;
Rat        rat;
Mouse      mou;
Look at the table and decide if each section of code is correct or not.


code sectionOK or Not?code sectionOK or Not?
rod = new Rat();

rod = new FieldMouse();

mou = new Rat();

mou = new Rodent();

rat = new Rodent();

rat = new LabRat();

rat = new FieldMouse();

rat = new Mouse();

QUESTION 15:

There is still much more to learn about inheritance and polymorphism.

Click Here after you have answered the question