LavaJab

1. Experiment 1:
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import java.util.Scanner;

public class ECommerceEntryExitControl {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int totalCustomers = 0;
        int currentCustomers = 0;
        boolean isOpen = false;

        // Entry Control Loop - Using do-while loop
        do {
            System.out.print("Enter '1' to open the store, '0' to exit: ");
            int choice = scanner.nextInt();

            if (choice == 1) {
                isOpen = true;
                System.out.println("Store is now open!");
                break;
            } else if (choice == 0) {
                System.out.println("Exiting the program...");
                return;
            } else {
                System.out.println("Invalid input, please try again.");
            }
        } while (true);

        // While loop to control customer entry and exit
        while (isOpen) {
            System.out.print("Enter '1' for a customer entering, '2' for a customer leaving, '0' to close the store: ");
            int action = scanner.nextInt();

            if (action == 0) {
                isOpen = false;
                break;
            } else if (action == 1) {
                currentCustomers++;
                totalCustomers++;
                System.out.println("Customer entered. Current customers: " + currentCustomers);
            } else if (action == 2) {
                if (currentCustomers > 0) {
                    currentCustomers--;
                    System.out.println("Customer left. Current customers: " + currentCustomers);
                } else {
                    System.out.println("No customers to leave.");
                }
            } else {
                System.out.println("Invalid input, please try again.");
            }
        }

        // Exit Control Loop - Using for loop
        System.out.println("Store is now closed.");
        System.out.println("Total customers served today: " + totalCustomers);
        scanner.close();
    }
}

2. Experiment 2:
--------->
import java.io.*;
import java.util.Scanner;

public class EcomSwitch {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        System.out.println("Welcome to the E-Commerce Store!");
        System.out.println("Select a product to view its price:");
        System.out.println("1. Laptop");
        System.out.println("2. Smartphone");
        System.out.println("3. Headphones");
        System.out.println("4. Exit");

        int choice;
        do {
            System.out.print("Enter your choice (1-4): ");
            choice = scanner.nextInt();

            switch (choice) {
                case 1:
                    System.out.println("Laptop: $800");
                    break;
                case 2:
                    System.out.println("Smartphone: $500");
                    break;
                case 3:
                    System.out.println("Headphones: $50");
                    break;
                case 4:
                    System.out.println("Thank you for visiting the store!");
                    break;
                default:
                    System.out.println("Invalid choice. Please enter a valid option.");
            }
        } while (choice != 4);

        scanner.close();
    }
}

3. Experiment 3:
-------->
import java.io.*;
import java.util.Scanner;

class Ecomm {
    public static void main(String args[]) throws IOException {
        Scanner d = new Scanner(System.in);
        String num[] = {"Soap", "Pencil", "Notebook", "Detergent(1 Kg)", "Pen", "Clothes"};

        System.out.println("Item present in List");
        for (int i = 0; i < num.length; i++) {
            System.out.println((i + 1) + ". " + num[i]);
        }

        System.out.print("Enter how many items you want to add: ");
        int m = d.nextInt();
        d.nextLine();

        String arr[][] = new String[m][2];
        for (int j = 0; j < m; j++) {
            System.out.print("Enter the item " + (j + 1) + ": ");
            arr[j][0] = d.nextLine();
            System.out.print("Enter the quantity: ");
            arr[j][1] = d.nextLine();
        }

        boolean itemsMatch = true;
        for (int j = 0; j < m; j++) {
            boolean found = false;
            for (int i = 0; i < num.length; i++) {
                if (arr[j][0].equalsIgnoreCase(num[i])) {
                    found = true;
                    break;
                }
            }
            if (!found) {
                itemsMatch = false;
                break;
            }
        }

        if (itemsMatch) {
            System.out.println("\nYour item\tQuantity\tPrice");
            for (int j = 0; j < m; j++) {
                double price = calculatePrice(arr[j][0].toLowerCase(), Integer.parseInt(arr[j][1]));
                System.out.println(arr[j][0] + "\t\t" + arr[j][1] + "\t\t$" + price);
            }
        } else {
            System.out.println("Your item list doesn't match with the items in the store.");
        }
    }

    private static double calculatePrice(String item, int quantity) {
        double pricePerUnit;
        switch (item) {
            case "soap":
                pricePerUnit = 1.0;
                break;
            case "pencil":
                pricePerUnit = 0.5;
                break;
            case "notebook":
                pricePerUnit = 2.0;
                break;
            case "detergent(1 kg)":
                pricePerUnit = 3.5;
                break;
            case "pen":
                pricePerUnit = 1.2;
                break;
            case "clothes":
                pricePerUnit = 10.0;
                break;
            default:
                pricePerUnit = 0.0; // Item not found in the list
        }

        return pricePerUnit * quantity;
    }
}