INHERITANCE AND POLYMORPHISM - Introduction to Java Programming: Comprehensive Version - page 445

P ROGRAMMING E XERCISES

Sections 11.2-11.4
11.1

( The Triangle class ) Design a class named Triangle that extends
GeometricObject . The class contains:

Three double data fields named side1 , side2 , and side3 with default
values 1.0 to denote three sides of the triangle.

■

A no-arg constructor that creates a default triangle.

■

A constructor that creates a triangle with the specified side1 , side2 , and
side3 .

■

The accessor methods for all three data fields.

■

A method named getArea() that returns the area of this triangle.

■

A method named getPerimeter() that returns the perimeter of this triangle. ■

■ A method named toString() that returns a string description for the triangle.
For the formula to compute the area of a triangle, see Programming Exercise 2.19.
The toString() method is implemented as follows:

return "Triangle: side1 = " + side1 + " side2 = " + side2 +
" side3 = " + side3;
Draw the UML diagrams for the classes Triangle and GeometricObject and
implement the classes. Write a test program that prompts the user to enter three
sides of the triangle, a color, and a Boolean value to indicate whether the triangle
is filled. The program should create a Triangle object with these sides and set
the color and filled properties using the input. The program should display
the area, perimeter, color, and true or false to indicate whether it is filled or not.
Sections 11.5-11.14
11.2 ( The Person , Student , Employee , Faculty , and Staff classes ) Design a

class named Person and its two subclasses named Student and Employee .
Make Faculty and Staff subclasses of Employee . A person has a name,
address, phone number, and email address. A student has a class status (freshman,
sophomore, junior, or senior). Define the status as a constant. An employee has
an office, salary, and date hired. Use the MyDate class defined in Programming
Exercise 10.14 to create an object for date hired. A faculty member has office
hours and a rank. A staff member has a title. Override the toString method in
each class to display the class name and the person's name.
Draw the UML diagram for the classes and implement them. Write a test pro-
gram that creates a Person , Student , Employee , Faculty , and Staff , and
invokes their toString() methods.

11.3

( Subclasses of Account ) In Programming Exercise 9.7 , the Account class was
defined to model a bank account. An account has the properties account number,
balance, annual interest rate, and date created, and methods to deposit and with-
draw funds. Create two subclasses for checking and saving accounts. A checking
account has an overdraft limit, but a savings account cannot be overdrawn.
Draw the UML diagram for the classes and then implement them. Write
a test program that creates objects of Account , SavingsAccount , and
CheckingAccount and invokes their toString() methods.

11.4

( Maximum element in ArrayList ) Write the following method that returns the
maximum value in an ArrayList of integers. The method returns null if the
list is null or the list size is 0 .
public static Integer max(ArrayList<Integer> list)