Java OOP

SHORT ANSWER QUESTIONS

INHERITANCE & POLYMORPHISM I

SOLUTIONS

1-Inheritance

2-is-a

3-class hierarchy

4-subclass, child

5-superclass, parent

6-extends

7-Tool

8-Foot

9-Diagram:

10a) Yes, we could use inheritance with these classes. Shape is the superclass and each of the other three have a is a relationship with Shape. For example, Circle is a Shape.

10b) None of these items are related to one another. A Cup is not a Marker or a Shoe or a House. Nothing else is a Cup. We can say the same for all other classes. So, no this is not a case where we could use inheritance.

10c) Yes, we can use inheritance here. Food could be Fruit’s superclass because Fruit is Food. Then, Fruit could be the superclass for the other three classes.

10d) No these are not suitable for inheritence. There is no superclass here. If we wanted to use inheritance, we would have to add a superclass such as Vegetable or Food.

10e) Not quite. While Missile can be the superclass for the next three classes, there is no obvious relationship between Cannon and Missile (or the other classes). So inheritance could be used for the first four terms, but not for Cannon.

11-instance variables, instance methods

12-overriding method

13-superconstructor, superclass

14-super

15-See the addition in blue in the code below.

Superclass	Subclass
public class Furniture { //implementation not shown }	public class Table extends Furniture { //implementation not shown }

16-When using super, the parameters much match the parameter lists of one of the superconstructors.

Superclass	Subclass
public class Character { //only the constructor is shown public Character(String n) { name = n; } }	public class Knight extends Character { //only the constructor is shown public Knight (String n, int lev) { super(); //or super("Alex"); level = lev; } }