EZTECH CheckOutSystem

import java.awt.*; // imports classes in the awt package
import java.awt.event.*; // imports classes in the awt.event package
import javax.swing.*; // imports classes in the swing package
import java.util.*; // imports classes in the java.util package

public class InventoryCheckoutSystem extends JFrame { // class that extends JFrame
// Declare constants
public static final int WIDTH = 400; // constant that defines the width of the window
public static final int HEIGHT = 500; // constant that defines the height of the window

// Declare instance variables
private HashMap<String, Product> inventory; // map that maps serial codes to products
private ArrayList<Product> cart; // list of products in the cart
private JLabel serialCodeLabel; // label for serial code text field
private JTextField serialCodeField; // text field for entering serial code
private JLabel quantityLabel; // label for quantity text field
private JTextField quantityField; // text field for entering quantity
private JButton addButton; // button for adding product to cart
private JButton checkoutButton; // button for checking out
private JLabel totalLabel; // label for total cost
private JLabel totalField; // field for displaying total cost
private JLabel Products; // field for displaying change due
private JLabel changeLabel; // label for change due
private JLabel changeField; // field for displaying change due
private JLabel amountPaidField; // field for displaying amount paid
private JScrollPane scrollPane;   //field for diplaying scrollbar
private JTextArea ProductArea;  // text area for displaying contents of cart


 public InventoryCheckoutSystem() {
// Set the title and size of the window
setTitle("EZTECH Checkout System"); // sets the title of the window
setSize(WIDTH, HEIGHT); // sets the size of the window
setVisible(true); // makes the window visible


// Set the layout to a grid layout
setLayout(new GridLayout(6, 10)); // sets the layout to a grid layout with 6 rows and 10 columns
// Initialize the inventory and cart
inventory = new HashMap<>(); // initializes the inventory as a hash map mapping serial codes to products
cart = new ArrayList<>(); // initializes the cart as an array list of products

// Add products to the inventory
inventory.put("28547", new Product("28547", "IdeaPad Slim 1i (14'', Gen 7)", 19000.00)); // adds a product with serial code "A1" to the inventory
inventory.put("74575", new Product("74575", "POCO X3 Pro", 14435.00));
inventory.put("53653", new Product("53653", "iPhone 12 Pro", 46599.00));
inventory.put("65783", new Product("65783", "Redragon Magic Wand K587 RGB TKL", 2099.00));
inventory.put("78655", new Product("78655", "Oppo Reno6", 26795.00));
inventory.put("94754", new Product("94754", "VIVO Y15A", 6999.00));
inventory.put("66764", new Product("66764", "XIAOMI Pad 5", 20999.00));
inventory.put("D4", new Product("D5", "Product D", 40.00));

// Initialize the GUI components
serialCodeLabel = new JLabel("Enter Product serial code: "); // label for serial code text field
serialCodeField = new JTextField(20); // text field for entering serial code
quantityLabel = new JLabel("Enter quantity: "); // label for quantity text field
quantityField = new JTextField(20); // text field for entering quantity
addButton = new JButton("Add to cart"); // button for adding product to cart
totalLabel = new JLabel("Total: "); // label for total cost
addButton = new JButton("Add to cart"); // button for adding product to cart

// Initialize the GUI components
Products = new JLabel("Your Cart: "); // field for displaying the contents of the cart
totalField = new JLabel(); // field for displaying the total cost of the products in the cart
checkoutButton = new JButton("Checkout"); // button for checking out
ProductArea = new JTextArea();  // create a new JTextArea object and assign it to the "ProductArea" instance variable
ProductArea.setEditable(false); // set the "ProductArea" to be non-editable
scrollPane = new JScrollPane(ProductArea);  // create a new JScrollPane object, which will wrap the "ProductArea" JTextArea, and assign it to the "scrollPane" instance variable
changeLabel = new JLabel("Change: "); // label for change due
changeField = new JLabel(); // field for displaying the change due
amountPaidField = new JLabel(); // field for displaying the amount paid by the user


   // Add the GUI components to the window

add(serialCodeLabel); // label for the serial code text field
add(serialCodeField); // text field for entering the serial code of the product
add(quantityLabel); // label for the quantity text field
add(quantityField); // text field for entering the quantity of the product
add(addButton); // button for adding the product to the cart
add(checkoutButton); // button for checking out
add(totalLabel); // label for the total cost
add(totalField); // field for displaying the total cost of the products in the cart
add(Products); // label for the contents of the cart
add(scrollPane);// text area for displaying the contents of the cart
scrollPane.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED);
add(changeLabel); // label for the change due
add(changeField); // field for displaying the change due

// Add action listeners to the buttons
addButton.addActionListener(new AddButtonListener()); // adds an action listener to the "Add to cart" button
checkoutButton.addActionListener(new CheckoutButtonListener()); // adds an action listener to the "Checkout" button
 }

 private class AddButtonListener implements ActionListener {
public void actionPerformed(ActionEvent e) {
// Get the serial code and quantity from the text fields
String serialCode = serialCodeField.getText().trim();
int quantity;
try {
quantity = Integer.parseInt(quantityField.getText().trim());
} catch (NumberFormatException exception) {
JOptionPane.showMessageDialog(null, "Invalid quantity.");
return;
}
 // Get the product with the specified serial code from the inventory
  Product product = inventory.get(serialCode);

  // If the product exists, add it to the cart the specified number of times
  if (product != null) {
    for (int i = 0; i < quantity; i++) {
      cart.add(product);
    }
    // Update the contents of the cart text area
  ProductArea.setText(getCartString());
  } else {
    // If the product does not exist, show an error message
    JOptionPane.showMessageDialog(null, "Product Not Found!");
  }

  // Clear the serial code and quantity text fields
  serialCodeField.setText("");
  quantityField.setText("");
}
}
  // Inner class for the action listener of the "Checkout" button
  private class CheckoutButtonListener implements ActionListener {
    public void actionPerformed(ActionEvent e) {
      // If the cart is empty, show an error message
      if (cart.isEmpty()) {
        JOptionPane.showMessageDialog(null, "Your cart is empty.");
      } else {
        // Calculate the total cost of the products in the cart
        double total = getTotal();
        // Format the total cost as a string with two decimal places
        String totalString = String.format("%.2f", total);
        // Display the total cost
        totalField.setText(totalString);

        // Show a dialog to get the amount paid from the user
        String amountPaidString = JOptionPane.showInputDialog(null, "Enter amount paid:");
        // Convert the input string to a double
       double amountPaid = Double.parseDouble(amountPaidString);
        amountPaidField.setText(String.valueOf(amountPaid));
       if (amountPaid < total) {
        // Show an error message if the amount paid is less than the total
        JOptionPane.showMessageDialog(null, "Amount paid is less than the total.(Please click Checkout Again)");
      } else {
        // Calculate the change due
        double change = amountPaid - total;
        // Format the change due as a string with two decimal places
        String changeString  = String.format("%.2f", change);
        // Display the change due
        changeField.setText(String.valueOf(changeString));

        // Show a message dialog with the receipt
        JOptionPane.showMessageDialog(null, getReceiptString());

        // Clear the cart and update the cart text area
        cart.clear();
        ProductArea.setText(getCartString());
        // Clear the total and change due fields
        totalField.setText("");
        changeField.setText("");
      }
      }
    }
  }



     private double getTotal() {
        // Declare variable to store total
        double total = 0;
        // Loop through the products in the cart
        for (Product p : cart) {
        // Add the price of the current product to the total
        total += p.getPrice();
        }
        // Return the total
        return total;
        }


        // Get a string representation of the contents of the cart
        private String getCartString() {
        String s = "";
        // Iterate through the cart and add each unique product to the string
        for (Product p : cart) {
        // Only add the product if it doesn't already exist in the string
        if (!s.contains(p.toString())) {
        // Find the number of times the product occurs in the cart
        int quantity = Collections.frequency(cart, p);
        // Add the product and its quantity to the string
        s += quantity + " x " + p + "\n";
        }
        }
        return s;
        }


        private String getReceiptString() {
          // Generate a random tracking number for the receipt
          Random random = new Random();
          int trackingNumber = random.nextInt();
          // Initialize the string with the tracking number
          String s = "Tracking number: " + trackingNumber + "\n";
          // Loop through the products in the cart
          for (Product p : cart) {
            // If the product's name is not already in the string, add the product and its quantity and price
            if (!s.contains(p.getName())) {
              int quantity = Collections.frequency(cart, p);
              s += quantity + " x " + p.getName() + ": " + p.getPrice() + "\n";
            }
          }
          // Add the total, amount paid, and change due to the string
          s += "Total: " + getTotal() + "\n";
          s += "Amount paid: " + amountPaidField.getText() + "\n";
          s += "Change: " + changeField.getText();
          // Add a thank you message
          s+="\nThank you for Shoping with us";
          // Return the string
          return s;
        }

            // Main method
           public static void main(String[] args) {
           InventoryCheckoutSystem window = new InventoryCheckoutSystem();
           window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
           window.setVisible(true);
           }
           }

           // Product class representing a product with a serial code, name, and price
            class Product {
            private String serialCode; // variable to hold the product serial code
            private String name; // variable to hold the product name
            private double price; // variable to hold the product price

            // constructor method to create a new product instance with a serial code, name, and price
            public Product(String serialCode, String name, double price) {
                this.serialCode = serialCode; // assign the serial code passed in to the serialCode variable
                this.name = name; // assign the name passed in to the name variable
                this.price = price; // assign the price passed in to the price variable
            }

            // method to get the serial code of the product
            public String getSerialCode() {
                return serialCode; // return the serial code of the product
            }

            // method to get the name of the product
            public String getName() {
                return name; // return the name of the product
            }

            // method to get the price of the product
            public double getPrice() {
                return price; // return the price of the product
            }

            // method to return a string representation of the product in the format: "serialCode: name (price)"
            public String toString() {
                return serialCode + ": " + name + " (" + price + ")"; // concatenate the serial code, name, and price with a colon, space, and parentheses to create the string
            }
        }