Question

An online retailer sells five products whose retail prices are as follows: Product \(1, \$ 2.98 ;\) product \(2, \$ 4.50 ;\) product \(3, \$ 9.98 ;\) product \(4, \$ 4.49\) and product \(5, \$ 6.87\) Write an application that reads a series of pairs of numbers as follows: a) product number b) quantity sold Your program should use a switch statement to determine the retail price for each product. It should calculate and display the total retail value of all products sold. Use a sentinel-controlled loop to determine when the program should stop looping and display the final results.

Short answer

To determine the total retail value, store product prices, use a sentinel-controlled loop to input product numbers and quantities, multiply these to update the total value, and display the final total.

Step-by-step solution

- Define Product Prices

Store the retail prices of each product in a data structure like a list or dictionary. For example, using a dictionary in Python: prices = {1: 2.98, 2: 4.50, 3: 9.98, 4: 4.49, 5: 6.87}.

- Initialize Total Value

Initialize a variable to keep track of the total retail value of all products sold. For example: total_retail_value = 0.

- Implement Sentinel-Controlled Loop

Use a while loop that continues to execute as long as a sentinel value hasn't been entered. For instance, a user can input 0 to stop the loop.

- Read Product Number and Quantity

Within the loop, prompt the user to input a product number and quantity sold. Parse the inputs to ensure they are the correct data type (integers).

- Use Switch Statement to Determine Price

Implement a switch or if-else statement to match the product number with its price using the previously defined price data structure.

- Calculate Product Total

Multiply the quantity of the product sold by the retrieved product price to get the total value for that product. For example: product_total = quantity * prices[product_number].

- Update Total Retail Value

Add the product total to the total retail value. For example, total_retail_value += product_total.

- Check for Sentinel Value

After processing each input, the loop should check whether the sentinel value has been entered to terminate the loop.

- Display Final Results

After exiting the loop, print the final total retail value to display to the user.

Key concepts

Sentinel-Controlled Loop

In Java programming, a sentinel-controlled loop, often implemented using a while or do-while loop, plays a crucial role in controlling the flow of execution based on user input or other conditions.

A sentinel value is a special value that signifies the end of a loop. This could be any value that is not part of the expected input, such as a negative number or zero, when only positive numbers are valid. In the context of a retail application, a sentinel value could be used to indicate that no more product data will be entered, and the program should proceed to calculate and display the final results.

Using a sentinel-controlled loop is efficient when the number of iterations is not known beforehand and depends on user input. For example, in a retail system, the store may not know in advance how many products will be sold in a particular session. Hence, they continue to input data until the special sentinel value is encountered, signaling the program to end the input phase and perform the final calculations.

Retail Price Calculation

Calculating retail prices effectively is essential in developing a system for an online retailer. It involves understanding the unit price of products and the quantity sold, and then applying the correct calculation to determine the total cost.

In a Java application designed to handle the sales operations, you would typically store retail prices in an array or a collection, such as a HashMap, where product IDs could be used as keys and prices as values. The price calculation involves accessing the price using a product ID and then multiplying it by the quantity of product sold. For instance, if product 1 sells for \(2.98 and a user purchases 10 units, the total price calculation would be 10 * 2.98, resulting in \)29.80 for that product. Summing up these individual product totals provides the complete retail value of all sales.

Displaying the calculated total retail price at the end of execution gives a clear and immediate understanding of the sales performance, which is invaluable for any retail business.

Java Programming Fundamentals

Understanding Java programming fundamentals is key when designing any kind of application, including a system for calculating retail sales. Core concepts such as data types, control structures (like loops and conditionals), and collections are foundational to creating a robust and efficient program.

In the given exercise, the fundamentals are perfectly exemplified by the need to store product prices and quantities, the use of a sentinel-controlled loop for input, and the implementation of a switch statement to handle the different product prices. A switch statement in Java is a control flow statement that allows variable values to be checked against predefined constants, known as case values, and execute specific blocks of code accordingly.

Getting these foundational aspects right ensures not only that your Java program will compile and run successfully but also ideally perform its tasks efficiently and reliably.

Program Design and Development

The design and development phase of creating an application is where the blueprint of the program is created and then implemented. This phase is critical to ensure that the program is not only functional but also user-friendly and maintainable.

In regards to a program for an online retailer, design considerations must include how product information is stored and accessed, the logic for input-processing loops, and the flow of control for price calculation and output. Careful planning of the overall structure and each function's interaction within the program can lead to a better software architecture that is easier to understand, debug, and extend.

During development, readable and consistent coding practices should be applied. Improving the given exercise could involve adding helpful prompts for the user, validating input to prevent errors, and perhaps implementing more object-oriented principles for greater scalability. Always remember to include comments and documentation so that others (or you in the future) can follow the logic of the program with ease.