Question

[Super Market Application] Supermarket sells many items every day. For each item sold, item code, quantity sold out and date of sales are represented in a class Sales with the following details: \- int itemCode, int quantity, Date sdate; Create a class SuperMarket with the members \- ArrayList \(<\) Sales \(>\) sales; \- public void sales(Date d) displays total sales on this date \- public void sales(int item) displays total sales based on itemCode \- public void sales() displays sorted list of all sales items based on sdate Design a public class that will create few sales details for this supermarket. Read a date from user and get the total sales on this particular date. Also, display total sales for the given itemCode. Finally, display complete sales details sorted datewise.

Short answer

Create Sales and SuperMarket classes. Implement sales methods for date, itemCode, and sorted list, then test by adding and querying data.

Step-by-step solution

- Create the Sales Class

Design the Sales class with the attributes: int itemCode, int quantity, and Date sdate. Implement a constructor to initialize these attributes.

- Create the SuperMarket Class

Design the SuperMarket class which includes an ArrayList of Sales objects named 'sales'.

- Implement sales(Date d) Method

In the SuperMarket class, implement a public method named sales(Date d) that iterates over the 'sales' ArrayList. Sum the quantities of items sold on the provided date and display the total.

- Implement sales(int item) Method

In the SuperMarket class, implement a public method named sales(int item) that iterates over the 'sales' ArrayList. Sum the quantities of the provided itemCode and display the total.

- Implement sales() Method

In the SuperMarket class, implement a public method named sales() that sorts the 'sales' ArrayList by date and then displays the sorted list.

- Add Sales Data

Create instances of the Sales class with arbitrary data and add them to the 'sales' ArrayList in the SuperMarket class.

- Read Date from User

Implement code to read a date from the user and pass it to the sales(Date d) method to display total sales for that date.

- Read itemCode from User

Implement code to read an itemCode from the user and pass it to the sales(int item) method to display total sales for that itemCode.

- Display All Sales

Call the sales() method to display the complete sales details sorted datewise.

Key concepts

Object-Oriented Programming

Object-Oriented Programming (OOP) is a paradigm in software development that focuses on organizing code into objects, each containing both data and methods. In our Java SuperMarket Application:
• The **Sales** class encapsulates the attributes `itemCode`, `quantity`, and `sdate`, representing a sale item, its quantity, and the date of sale respectively.
• The **SuperMarket** class holds an `ArrayList` that manages a collection of sale objects and includes methods to perform various operations like displaying total sales based on date or item code.
OOP promotes reusability, modularity, and maintainability by allowing you to create complex applications by combining simpler building blocks. Understanding how class and object interaction works is crucial for following this example and writing your own Java programs.

ArrayList in Java

Java's `ArrayList` is a resizable array implementation of the `List` interface. Unlike standard arrays, `ArrayList` can adjust its size dynamically. In the SuperMarket application, the `ArrayList` plays a critical role:
• It **stores multiple Sales objects**.
• It allows **easy iteration** over sales for performing operations like summing quantities or displaying sorted lists.
**Key Methods to Remember**:
- `add(Sales s)`: Adds a Sales object to the list.
- `get(int index)`: Returns the Sales object at the specified position.
- `size()`: Returns the number of elements in the list.
- `sort(Comparator c)`: Sorts the list based on a comparator.
Understanding the use of `ArrayList` helps in managing and manipulating collections of data efficiently in Java.

Java Date Handling

Handling dates in Java involves using classes from the `java.util` package, such as `Date`. The SuperMarket application uses `Date` to track when each sale occurs. Here's how it works:
**Key Points**:
- **Instantiation**: You can create a Date object using `new Date()` which initializes it to the current date and time.
- **Formatting**: The `SimpleDateFormat` class helps in parsing and formatting date strings.
- **Comparison**: Dates can be compared using methods like `before(Date date)`, `after(Date date)`, and `equals(Object date)`.
For instance, when implementing the `sales(Date d)` method, you iterate through the sales list and compare each sale's date with the provided date to accumulate the total sales. Mastery of date handling is essential for applications dealing with temporal data.

User Input in Java

Interacting with users involves reading input from the console. The SuperMarket application uses the `Scanner` class to take user inputs such as a date or an item code.
Here are the steps:
1. **Create a Scanner object**: `Scanner sc = new Scanner(System.in);`
2. **Read input**:
• For integers: `int itemCode = sc.nextInt();`
• For strings (dates): `String dateInput = sc.next();` followed by parsing it into a Date object using `SimpleDateFormat`.
• Close the Scanner object after use: `sc.close();`
Capturing user input efficiently enables dynamic interaction in Java applications, making your programs more responsive and user-friendly.

Sorting in Java

Sorting collections is a fundamental task in many applications. In Java, the `Collections.sort()` method is used together with a `Comparator` to define custom sorting logic. For the SuperMarket application:
Your task is to sort sales based on the date (`sdate`).
**Steps**:
1. **Create a Comparator**: Define how two Sales objects should be compared using the `compare` method.
```java
Comparator dateComparator = new Comparator() {
public int compare(Sales s1, Sales s2) {
return s1.sdate.compareTo(s2.sdate);
}
};
```
2. **Sort the list**: Use `Collections.sort(sales, dateComparator);`
This snippet sorts the sales by date, which you can then display. Mastering sorting techniques is imperative for managing ordered data efficiently in Java.