SANTA CLARA UNIVERSITY

Computer Engineering Department COEN 120 Real Time Systems

Homework 2 (Inheritance, Abstract Class, Interface)

(15 points)

For each of the following programs, compile and execute the program and submit the code as

well as the output. Programs must contain comments and should use an appropriate indentation

style.

1. What is the difference between an abstract class and an interface?

2. Create three classes Mouse, Gerbil and Hamster that have a common superclass called

Rodent. In the base class Rodent, provide methods that are common to all rodents, and

override these in the derived classes to perform different types of behaviors depending on

the specific type of Rodent. Create an array of Rodent, fill it with different specific types

of Rodents, and call your base class methods to see what happens.

3. Create a class as abstract without including any abstract methods, and verify that you

cannot create an instance of that class.

4. Modify the Rodent class in Example 1 so that it is an abstract class. Make the methods of

Rodent abstract whenever possible.

5. (a) Write an interface calls Instrument with two methods:

void play(String notes);

void adjust();

(b) Write two classes called Wind and Percussion that implement this interface. The

method body contains a print statement to display a message containing the name of the

class and the method name on the screen.

(c) Write a class called Brass that extends Wind and does not define any methods.

(d) Write a class called Woodwind that extends Wind and does not define any methods.

(e) Write a new class called Music that contains a main method. In main, create an

instance of the Brass, Woodwind and Percussion classes. Each instance calls its play

method.