Description
Overview: This week you will complete the first part of a three-part software project to process the
monthly purchases made by credit card company’s cardholders. Part 1 of the project focuses on the
implementation of the classes of cardholders. The completed class hierarchy is shown in the UML
class diagram below.
Project 9: Cardholders – Part 1 Page 2 of 8
Cardholder.java
Requirements: The Cardholder class is an abstract class from which other cardholder classes are
derived. It contains fields and methods that will be inherited by the classes derived from Cardholder.
Design: The Cardholder class has fields, a constructor, and methods as outlined below.
(1) Fields: category, acctNumber, name (all String objects), prevBalance of type double, payment of
type double, an array of type double representing new purchases; and a public constant
INTEREST_RATE set to 0.01 (a double). The instance variables should be protected rather than
private.
(2) Constructor: The constructor accepts String objects for the card holder’s acctNumber and name
as and assigns the fields accordingly. The constructor should also create the purchases array of
type double with initial length of 0 and assign the field.
(3) Methods: Usually a class provides methods to access and modify each of its instance variables
(i.e., getters and setters) along with any other required methods. The methods for Cardholder are
described below.
o getAcctNumber and setAcctNumber are the getter and setter methods for the
acctNumber fields. The getter accepts no parameters and returns a String. The set method
accepts a String and does not return a value.
o getName and setName are the getter and setter methods for the name field. The getter
accepts no parameters and returns a String. The set method accepts a String and does not
return a value.
o getPrevBalance and setPrevBalance are the getter and setter methods for the
previous balance field. The set method accepts a double and does not return a value. The
getter accepts no parameters and returns a double.
o getPayment and setPayment are the getter and setter methods for the payment field.
The set method accepts a double and does not return a value. The getter accepts no
parameters and returns a double.
o getPurchases and setPurchases are the getter and setter methods for the purchases
array field. The set method accepts a double[] and does not return a value. The getter accepts
no parameters and returns a double[].
o addPurchases has no return value and accepts a variable length parameter list of type
double and adds the double values in the list to the purchases array (see end notes). Before
values are added, the purchases array should be copied and replaced with a new array of
appropriate length so that the length of the array reflects the number of values in the array.
Note that java.util.Arrays contains a static method called Arrays.copyOf which takes two
parameters (double[] orginal, int newLength) and returns the copy of the array with increased
or decreased length. For example, the following statement makes a copy of an array called
purchases and with the length increased by 1, and then replaces the previous array with the
new one.
purchases = Arrays.copyOf(purchases, purchases.length + 1);
o deletePurchases has no return value and accepts a variable length parameter list of type
double and deletes them from the purchases array. A value is deleted from the purchases
array by locating the value to be removed and then copying each element to the right one
Project 9: Cardholders – Part 1 Page 3 of 8
place to the left, thus, overwriting the element to be removed. The purchases array should be
copied and replaced with a new array which has a length one less than the previous array so
that the length of the array reflects the number of values in the array. If a value to be deleted
is not found in the purchases array, then the array is left unchanged. You may want to create a
private method that deletes a single purchase and then call it from the deletePurchases
method described here as it loops through the array of purchases to be deleted.
o interest returns double calculated as (previous balance – payment) * INTEREST_RATE.
o totalPurchases returns a double based on the total of the items in the purchase array.
o balance returns a double representing previous balance with interest plus the total
purchases.
o currentBalance returns a double calculated as follows:
previous balance – payment + interest + total of new purchases;
o minPayment returns double calculated as 3% of current balance.
o toString returns a String describing a Cardholder (see example output below). This
method should use a DecimalFormat object with the pattern (“$#,##0.00”) to format the
values representing dollars and a DecimalFormat object with the pattern (“#,##0”) to format
the values representing purchase points as shown in the example return value for a
SapphireCardholder.
Sapphire Cardholder
AcctNo/Name: 10001 Smith, Sam
Previous Balance: $1,200.00
Payment: ($200.00)
Interest: $10.00
New Purchases: $548.00
Current Balance: $1,558.00
Minimum Payment: $46.74
Purchase Points: 548
o purchasePoints is an abstract method that returns an int representing the purchase
points earned on the total purchases in the purchases array.
Code and Test: Since the Cardholder class is abstract you cannot create instances of Cardholder upon
which to call the methods. However, these methods will be inherited by the subclasses of Cardholder.
You should consider first writing skeleton code for the methods in order to compile Cardholder so that
you can create the first subclass described below. At this point you can begin completing the methods
in Cardholder and writing the JUnit test methods for your subclass that tests the methods in
Cardholder.
SapphireCardholder.java
Requirements: The SapphireCardholder class is derived from the Cardholder class. Objects of this
class will receive one purchase point per dollar spent.
Design: The Preferred class has fields, constructor, and methods as outlined below.
Project 9: Cardholders – Part 1 Page 4 of 8
(1) Fields: No fields are added. Note that category, acctNumber, name, prevBalance, payment,
purchases array, and INTEREST_RATE are inherited from Cardholder.
(2) Constructor: The constructor accepts String objects for the card holder’s acctNumber and name
and passes them to the super class’s constructor. It should also set the category field to “Sapphire
Cardholder”.
(3) Methods: The methods in Cardholder are inherited; the following methods need to be added:
o purchasePoints overrides the abstract method inherited from the Cardholder and returns
an int calculated at one point per whole dollar of the total purchases in the purchases array.
Code and Test: Since the parent of this class was abstract, the inherited methods, as well as the
method created in this class, should be tested in the JUnit test file for this class. You will need to
complete any inherited methods that have not been completed. It is common to complete the methods
in the source files as you develop the associated test methods in the JUnit test file. You also may want
create a driver class with a main method that creates instances of the class, sets fields as appropriate,
and invokes the toString method and perhaps others to get you started.
DiamondCardholder.java
Requirements: The DiamondCardholder class is derived from the Cardholder class. An Object of this
class will receive three purchase points per dollar spent as well as a 5% discount on the subtotal.
Design: The DiamondCardholder class has fields, constructor, and methods as outlined below.
(1) Fields: Adds a field for discountRate set to .05, a double. Other fields are inherited from
Cardholder. This instance variable should be protected rather than private.
(2) Constructor: The constructor accepts String objects for the customer’s acctNumber and name and
passes them to the super class’s constructor. It should also set the category field to “Diamond
Cardholder”.
(3) Methods: The methods in Cardholder are inherited; the following methods need to be added:
o getDiscountRate and setDiscountRate are the getter and setter methods for the
discountRate field. The getter accepts no parameters and returns a double. The set method
accepts a double and does not return a value.
o purchasePoints overrides the abstract method inherited from the Cardholder and returns
an int calculated at 3 points per dollar of the total purchases in the purchases array.
o totalPurchases overrides the inherited totalPurchases method to include the
discount indicated by the discountRate field.
o toString overrides the inherited toString to return a String that includes a statement that a
discount was applied to subtotal (see example return value below). This method should use a
DecimalFormat object with the pattern (“0.0%”) to format the discount rate.
Diamond Cardholder
AcctNo/Name: 10002 Jones, Pat
Previous Balance: $1,200.00
Payment: ($0.00)
Interest: $12.00
New Purchases: $473.10
Project 9: Cardholders – Part 1 Page 5 of 8
Current Balance: $1,685.10
Minimum Payment: $50.55
Purchase Points: 1,419
(includes 5.0% discount rate applied to New Purchases)
Code and Test: As this class and its methods are implemented, the methods should be tested in the
JUnit test file for this class. You also may want create a driver class with a main method that creates
instances of the class, sets fields as appropriate, and invokes the toString method and perhaps others to
get you started.
BlueDiamondCardholder.java
Requirements: The BlueDiamondCardholder class is derived from the DiamondCardholder class. An
Object of this class will receive five purchase points per dollar spent as well as a 10% discount on the
subtotal. Also, if the new purchases exceed $2,500.00, a bonus of 2,500 purchase points is earned.
Design: The BlueDiamondCardholder class has fields, constructor, and methods as outlined below.
(1) Fields: Adds a field for bonusPurchasePoints set to 2500, an int. Other fields are inherited from
Cardholder and DiamondCardholder. This instance variable should be private.
(2) Constructor: The constructor accepts String objects for the customer’s acctNumber and name and
passes them to the super class’s constructor. The category field should be set to “Blue Diamond
Cardholder” and the discountRate should be set to 0.10 in constructor.
(3) Methods: The methods in Cardholder are inherited; the following methods need to be added:
o getBonusPurchasePoints and setBonusPurchasePoints are the getter and
setter methods for the bonusPurchasePoints field. The getter accepts no parameters and
returns an int. The set method accepts an int and does not return a value.
o purchasePoints overrides the inherited method and returns an int calculated at 5 points
per dollar of the total purchases in the purchases array. If the total is greater than $2,500.00,
the value of bonusPurchasePoints is also added.
o toString overrides the inherited toString to returns a String that includes the toString of
the superclass and if the subtotal is greater than $2,500, a statement indicating that bonus
points were added to the purchase points (see examples of two return values below). This
method should use a DecimalFormat object with the pattern (“#,##0”) to format the bonus
purchase points.
Blue Diamond Cardholder
AcctNo/Name: 10003 King, Kelly
Previous Balance: $1,200.00
Payment: ($0.00)
Interest: $12.00
New Purchases: $538.20
Current Balance: $1,750.20
Minimum Payment: $52.51
Purchase Points: 2,690
Project 9: Cardholders – Part 1 Page 6 of 8
(includes 10.0% discount rate applied to New Purchases)
Blue Diamond Cardholder
AcctNo/Name: 10004 Jenkins, Jordan
Previous Balance: $1,200.00
Payment: ($0.00)
Interest: $12.00
New Purchases: $9,000.00
Current Balance: $10,212.00
Minimum Payment: $306.36
Purchase Points: 47,500
(includes 10.0% discount rate applied to New Purchases)
(includes 2,500 bonus points added to Purchase Points)
Code and Test: As this class and its methods are implemented, the methods should be tested in the
JUnit test file for this class. You also may want create a driver class with a main method that creates
instances of the class, sets fields as appropriate, and invokes the toString method and perhaps others to
get you started.
Project 9: Cardholders – Part 1 Page 7 of 8
Example Cardholder Objects and Output (generated by the toString methods)
SapphireCardholder sc = new SapphireCardholder(“10001”, “Smith, Sam”);
sc.addPurchases(34.5, 100.0, 63.50, 350.0);
sc.setPrevBalance(1200.0);
sc.setPayment(200);
System.out.println(sc + “\n”);
DiamondCardholder dc = new DiamondCardholder(“10002”, “Jones, Pat”);
dc.addPurchases(34.5, 100.0, 63.50, 300.0);
dc.setPrevBalance(1200.0);
System.out.println(dc + “\n”);
BlueDiamondCardholder bdc = new BlueDiamondCardholder(“10003”, “King, Kelly”);
bdc.addPurchases(34.5, 100.0, 63.50, 300.0, 100.0);
bdc.setPrevBalance(1200.0);
System.out.println(bdc + “\n”);
BlueDiamondCardholder bdc2 = new BlueDiamondCardholder(“10004”, “Jenkins, Jordan”);
bdc2.addPurchases(5000.0, 1000.0, 4000.0);
bdc2.setPrevBalance(1200.0);
System.out.println(bdc2 + “\n”);
Output:
Sapphire Cardholder
AcctNo/Name: 10001 Smith, Sam
Previous Balance: $1,200.00
Payment: ($200.00)
Interest: $10.00
New Purchases: $548.00
Current Balance: $1,558.00
Minimum Payment: $46.74
Purchase Points: 548
Diamond Cardholder
AcctNo/Name: 10002 Jones, Pat
Previous Balance: $1,200.00
Payment: ($0.00)
Interest: $12.00
New Purchases: $473.10
Current Balance: $1,685.10
Minimum Payment: $50.55
Purchase Points: 1,419
(includes 5.0% discount rate applied to New Purchases)
Blue Diamond Cardholder
AcctNo/Name: 10003 King, Kelly
Previous Balance: $1,200.00
Payment: ($0.00)
Interest: $12.00
New Purchases: $538.20
Current Balance: $1,750.20
Minimum Payment: $52.51
Purchase Points: 2,690
(includes 10.0% discount rate applied to New Purchases)
Blue Diamond Cardholder
AcctNo/Name: 10004 Jenkins, Jordan
Previous Balance: $1,200.00
Project 9: Cardholders – Part 1 Page 8 of 8
Payment: ($0.00)
Interest: $12.00
New Purchases: $9,000.00
Current Balance: $10,212.00
Minimum Payment: $306.36
Purchase Points: 47,500
(includes 10.0% discount rate applied to New Purchases)
(includes 2,500 bonus points added to Purchase Points)
Notes
Below is an example of a variable length parameter list of type double ter declared in a method:
myMethod(double… myList)
where myMethod is the method name and myList is the name of the array where the double values
will be collected. Here are several examples of how myMethod can be called. Variables of type double
could be used in place of the double literals.
myMethod(12.25);
myMethod(12.25, 23.43);
myMethod(12.25, 23.43, 14.19, 45.67);
double dArr = {12.25, 23.43, 14.19, 45.67};
myMethod(dArr)
