Retail Transaction Programming Project




Project Requirements:
1. Develop a program to emulate a purchase transaction at a retail store. This
program will have two classes, a LineItem class and a Transaction class. The
LineItem class will represent an individual line item of merchandise that a
customer is purchasing. The Transaction class will combine several LineItem
objects and calculate an overall total price for the line item within the transaction.
There will also be two test classes, one for the LineItem class and one for the
Transaction class.
2. Design and build a LineItem class. This class will have three instance variables.
There will be an itemName variable that will hold the identification of the line item
(such as, “Colgate Toothpaste”); a quantity variable that will hold the quantity of
the item being purchased; and a price variable that will hold the retail price of the
item. The LineItem class should have a constructor, accessors for the instance
variables, a method to compute the total price for the line item, a method to
update the quantity, and a method to convert the state of the object to a string.
Using Unified Modeling Language (UML), the class diagram looks like this:
– itemName : String
– quantity : int
– price : double
+ LineItem( String, int, double )
+ getName( ) : String
+ getQuantity( ) : int
+ getPrice( ) : double
+ getTotalPrice( ) : double
+ setQuantity( int )
+ setPrice( double )
+ toString( ) : String
a. The constructor will assign the first parameter to the instance variable
itemName, the second parameter to the instance variable quantity, and
the third parameter to the instance variable price.
b. The class will have three accessor methods—getName( ), getQuantity( ),
and getPrice( )—that will return the value of each respective instance
© 2014 Laureate Education, Inc. Page 2 of 4
c. The class will have two mutator methods, setQuantity( int ) and setPrice(
double ), that will update the quantity and price, respectively, of the item
associated with the line of the transaction.
d. The method getTotalPrice( ) handles the conversion of the quantity and
price into a total price for the line item.
e. The method toString( ) allows access to the state of the object in a
printable or readable form. It converts the variables to a single string that
is neatly formatted.
Note: Refer to the textbook for a discussion of escape sequences. These
are characters that can be inserted into strings and, when printed, will
format the display neatly. An escape sequence for the tab character can
be inserted to get a tabular form when printing. This tab character is “\t”.
The LineItem class will have a toString( ) method that concatenates
itemName, quantity, price, and total price—separated by tab
characters—and returns this new string. When printing an object, the
toString( ) method will be implicitly called, which in this case, will print a
string that will look something like:
Colgate Toothpaste qty 2 @ $2.99 $5.98
3. Build a Transaction class that will store information about the items being
purchased in a single transaction. It should include a customerID and
customerName. It should also include an ArrayList to hold information about
each item that the customer is purchasing as part of the transaction.
Note: You must use an ArrayList, not an array.
4. Build a TransactionTest class to test the application. The test class should not
require any interaction with the user. It should verify the correct operation of the
constructor and all methods in the Transaction class.
Specific Requirements for the Transaction Class
1. The Transaction class should have a constructor with two parameters. The first
is an integer containing the customer’s ID and the second is a String containing
the customer’s name.
2. There should be a method to allow the addition of a line item to the transcript.
The three parameters for the addLineItem method will be (1) the item name, (2)
the quantity, and (3) the single item price.
3. There should be a method to allow the updating of a line item already in the
transaction. Notice that updating an item means changing the quantity or price
(or both). The parameters for the updateItem method are also (1) the item name,
(2) the quantity, and (3) the single item price. Notice that the updating of a
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specific line item requires a search through the ArrayList to find the desired
item. Anytime a search is done, the possibility exists that the search will be
unsuccessful. It is often difficult to decide what action should be taken when such
an “exception” occurs. Since exception handling is not covered until later in this
textbook, make some arbitrary decisions for this project. If the item to be updated
is not found, take the simplest action possible and do nothing. Do not print an
error message to the screen. Simply leave the transaction unchanged.
4. The transaction class needs a method called getTotalPrice to return the total
price of the transaction.
5. There should also be a method to return information about a specific line item. It
should return a single String object in the same format described for the
LineItem class:
Colgate Toothpaste qty 2 @ $2.99 $5.98
Again, the possibility exists that the search for a specific line item will fail. In this
instance, you should return a string containing a message similar to this:
Colgate Toothpaste not found.
6. The final method needed is a toString method. It should return the transaction
information in a single String object. It should use the following format:
Customer ID : 12345
Customer Name : John Doe
Colgate Toothpaste qty 2 @ $2.99 $5.98
Bounty Paper Towels qty 1 @ $1.49 $1.49
Kleenex Tissue qty 1 @ $2.49 $2.49
Transaction Total $9.96
Notice that a newline character “\n” can be inserted into the middle of a string.
int age = 30;
String temp = “John Doe \n is ” + age + “\n” + ” years
The output would be:
John Doe
is 30
years old
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Notice also that “\n” is a single character and could actually go inside single or
double quotes, depending on the circumstances.
Here is a UML diagram for the Transaction class as described above. Notice that
private instance variables and methods may be added, as needed. For all public
methods use exactly the name given below.
– lineItems : ArrayList<LineItem>
– customerID : int
– customerName : String
+ Transaction( int, String )
+ addLineItem( String, int, double )
+ updateItem( String, int, double )
+ getTotalPrice( ) : double
+ getLineItem( String ) : String
+ toString( ) : String