Description
Starberk’s coffee replenishment system – part 2
This assignment will use basically the same ideas from the first assignment, but the number of products is not fixed. The
user can add products and also delete them. You will also include a feature to load products using an external file.
Problem specification
Starberk’s coffee has asked you to create a system to enable them to manage the replenishment of different products
they sell in two different stores (LambtonStore and CallaghanStore). Each product has the following information: name,
demand rate, setup cost, unit cost, inventory cost and selling price. Demand rate is a fixed demand per week. The setup
cost is a fixed cost that Starberk’s coffee needs to pay every time they make an order, regardless of the quantity. The
inventory cost is the cost for each product unit in the inventory per week.
The dilemma is if Starberk’s Coffee asks for a big quantity order to cover the whole month, for example, they will spend a
lot of money in inventory. On the other hand, if they decide to make an order every week they will spend a lot in setup,
since every time they ask for an order they need to pay a setup cost.
There is a method called the EOQ (Economic Order Quantity) which calculates the optimal order quantity, if you know the
following information:
Demand rate
Inventory cost/unit/week
Setup cost
The EOQ method calculates the optimal order quantity that would minimize total variable costs, by using the formula
below
Q =
Where s = setup cost
d = demand/week
h= inventory cost/unit/week
An example:
Suppose that you know the demand rate for coffee is 45/week, h = 0.60 (inventory cost per unit per week) and s = 132
(setup cost). With these values, you can calculate the value of Q which will be 140.71. Suppose that you can just order
integer values, so rounding 140.71 we will have Q=141. Now, you can find the replenishment strategy for the next n
weeks. Let’s suppose 6 weeks. In the first week the order will be 141 units, but the demand is only 45 units, then it will
have 96 units in the inventory. In the second week the demand is 45 units and we have 96 units in the inventory from
week 1. So, the second week will finish with 51 units. Then week 3 will finish with 6 units in the inventory. By week 4,
there is not enough units in the inventory, so we need to make a new order, and so on. So, the replenishment strategy for
next 6 weeks will be
Week Quantity Order Demand Inventory
1 141 45 96
2 0 45 51
3 0 45 6
4 141 45 102
5 0 45 57
6 0 45 12
Notice that the inventory finishes with 12 units. This is not necessary; it is better the inventory finishes with 0 units. So, we
can do some arrangements. Just change the last order from 141 to (141-12). So the best replenishment strategy for next
6 weeks will be
Week Quantity Order Demand Inventory
1 141 45 96
2 0 45 51
3 0 45 6
4 129 45 90
5 0 45 45
6 0 45 0
Now, let’s calculate the total cost and the total profit. Suppose the unit cost is 1 and the selling price is 3. The total cost
will be
Purchase = (132+132) + (141+129)*1 = 264+270 = 534
Inventory = (96+51+6+90+45)*0.6 = 172.80
Total cost = 534+172.8 = 706.80
The profit will be
Profit = 45*6*3 – 706.8 = 810 – 706.8 = 103.20
For this assignment, you will write a program that will calculate and print the replenishment strategy for a product for n
weeks and find the total profit. In the end, the program will ask the user if he/she would like to restart for another product.
Programming Requirements
When the program starts, a 2 tier menu system will be available, where the user will have the following menu options:
1. Choose Store
{callaghan, lambtom}
1. Add/Edit product
2. Delete product
3. Display product
4. Display all products
5. Exit Store
2. Display stores
3. Open
4. Save
5. Exit
The description of each option is below.
● 1. Choose Store. The user chooses a store (Lambton or Callaghan). The input name must be a string from the set
{callaghan, lambton}. The user can use lower case or upper case, but the program will always convert to lower case. If
the user inputs a string that does not belong to the set, then the program will show an error message and ask the input
again. Next, the user will have the options below.
o 1. Add/Edit product: input data for one product. The program will ask the name of the product. The user
can use lower case or upper case, but the program will always convert to lower case. It will also be
possible to have space within the name of the product (such as “Tic Tacs”). If the user inputs a name that
already exists, then the program will show a message and the user will have 2 options: (1) input another
name or (2) change the data of this product.
o 2. Delete product: If the store does not have any products, the program will display the message “no
products” and go back the second level menu options Add/Edit product, Delete product, Display product,
Display all products. If the store has products, the list of product names will be displayed and the user will
be asked to input the product name. Then, the program will delete the product and will display the
message “the product was deleted”. If the name is not found, the program will display the message “the
product does not exist” and go back to the second level menu options.
o 3. Display product: If the store does not have any products, the program will display the message “no
products” and go back the second level menu options Add/Edit product, Delete product, Display product,
Display all products. If the store has products, the list of product names will be displayed and the user will
be asked to enter the product name. If the name is not found, the program will display the message “the
product does not exist” and go back to the second level menu options. If the name is found, the program
will display all information about the product (name, demand, setup cost, unit cost, inventory cost and
selling price), then, the program will ask if the user would like to see the replenishment strategy. If yes,
the program will ask the number of weeks and it will display replenishment strategy, total cost and profit.
If the name is not found, the program will display the message “the product does not exist”.
Note: for some inputs, the EOQ method will not give a feasible plan. For example, if setup cost is 5,
demand rate is 100 and inventory cost is 1, then the Q = 31.6, which does not cover even the demand for
the first week. If the value of Q is not a feasible value (if it is less than the demand rate), then the program
will give an error message to the user saying “It is not possible to have a replacement strategy with the
inputs given, please edit the product details” and go back to the second level menu options.
o 4. Display all products: If the store does not have any products, the program will display the message
“no products” and go back the second level menu options Add/Edit product, Delete product, Display
product, Display all products. If the store has products, the program will display the following information
(name, demand, setup cost, unit cost, inventory cost and selling price) of each product. The details
should be displayed neatly in columns, with a header row displaying the content for each column.
setup unit cost
o 5. Exit Store. The program will go back to the options choose store, display store, open, save, exit.
Note: Data validation is required for any input provided by a user. All product names must be within 3
and 10 characters in length. All number inputs must be positive. If the user inputs an invalid product
name or negative input, the program will show a message and ask the input again.
● 2. Display Stores: The program will display information about the stores as in the example below:
Store: Lambton
Number of products: 0
Store: Callaghan
Number of products: 2
Product 1: name
Product 2: name
Note: if products exist, only the product name needs to be displayed.
● 3. Open: This option will load products to a store via batch uploading/file reading. The file can contain information for
each store. For this option, the user needs to input the file name. If the file does not exist the program will display the
message “the file does not exist” and will go back to the main menu, choose store, display store, open, save, exit. If the
file exists, the program will read the information of the products in this file and add them to the list of exisitng products
(if any) to the required store. You will find an example input file named “Input.dat” in Blackboard. You can assume that
any files used in the program will match the format of this provided file. You can also assume that any product details
in the file will contain valid data, so data validation will not be required for this option.
● 4. Save: The user will input a file name (name only) and the program will save the details of the store to a file with a
.dat extension. The program will save any information which is current for the store, in the same format of “Input.dat”.
If the user enters “Input” as their file name, then the details in the system will overwrite those in the file.
● 5. Exit. The program will end.
To write this program, there must be three classes: Product, Store, StarberksInterface
The Product Class (the file needs to be Product.java)
It will hold the required instance data for a product and it will have suitable methods to access and modify the data for a
product. It will also have a toString method. The methods will be public and the instance variables will be private.
Implement two constructors; one default constructor and one paramatized constructor.
The Store Class (the file needs to be Store.java)
It will hold the required instance data for a store and it will have suitable methods to access and modify the data of a
store. It must have a one-dimensional array of Product as an instance variable. It must use the Product class’s methods
for accessing and modifying the data in a product object. The product array will be instantiated with 3 positions. You need
to use a method resizeArray to add a position for a new product when necessary. This class should not use libraries
for any array functionality. The class will also have a toString method. The methods will be public and the instance
variables will be private.
The StarberksInterface Class (the file needs to be StarberksInterface.java)
Creates the interface (TerminalIO or GUI, you choose).
This class will have two Store objects as instance variables: LambtonStore and CallaghanStore
This class will receive all input from the user, display all output, check for invalid inputs and display all error messages.
No other class should have GUI or TIO operations. That is, the class StarberksInterface will be the only one that will
receive inputs and show outputs.
All the data components of all your classes need to be private (this means that you are applying the principles of
encapsulation). Additionally, your classes need to have methods that provide the functionality outlined in the problem
description. The only class which should have a main method is StarberksInterface.java, which should create an
instance of the class and call the run() method which will have code to provide the user with a menu system to allow them
to perform any of the tasks outlined in the problem description. The template for this is below.
public class StarberksInterface
{
private void run()
{
//This method should control the flow of the program
}
public static void main(String[] args)
{
StarberksInterface intFace = new StarberksInterface();
intFace.run();
}
}
What to submit.
You should submit the Java files (Product.java, Store.java, StarberksInterface.java), the documentation and the
assignment cover sheet electronically using the Blackboard. Your code also must be very well commented and
organized.
For submission, please zip the folder you wish to submit, named c_SENG1110_Assignment2
Example:
cXXXXXXX_SENG1110_Assignment2.zip
Files which will need to be included with the submission are:
Product.java
Store.java
StarberksInterface.java
Assessment Coversheet
Extra Work for SENG6110 students
When the user chooses the option “display all products”, the program will display the information sorted by name or
demand (the user will choose). You need to implement a sort algorithm.
SENG1110 students that implement the SENG6110 task will receive extra marks.
In the Blackboard you will find a new forum in the discussion board: “Assignment2”. Any question about the
assignment 2 you can post there. Check this forum regularly.
