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Retail Transaction Programming Project

Retail Transaction Programming Project

You will then create a new project in NetBeans to implement Programming Project 1.


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 

variable. © 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 © 2014 Laureate Education, Inc. Page 3 of 4

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© 2014 Laureate Education, Inc. Page 4 of 4

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