MainClass.java

import java.util.*;

public class MainClass {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        empServices service = new empServices();
        boolean exit = false;

        while (!exit) {
            System.out.println("\n=== Employee Management Menu ===");
            System.out.println("1. Insert New Employees");
            System.out.println("2. View All Employees");
            System.out.println("3. View Sorted Employees by Name");
            System.out.println("4. View Employees from Noida");
            System.out.println("5. Exit");
            System.out.print("Enter your choice (1-5): ");

            String choice = sc.nextLine().trim();

            switch (choice) {
                case "1":
                    insertEmployees(sc, service);// new change 
                    break;
                case "2":
                    displayEmployees(service.selectFromTable());
                    break;
                case "3":
                    List<Employee> sorted = service.selectFromTable();
                    service.arraySortComparator(sorted);
                    break;
                case "4":
                    List<Employee> allEmp = service.selectFromTable();
                    List<Employee> noidaEmp = service.getNoidaEmp(allEmp);
                    displayEmployees(noidaEmp);
                    break;
                case "5":
                    System.out.println("Exiting...");
                    exit = true;
                    break;
                default:
                    System.out.println("Invalid choice. Please try again.");
            }
        }

        service.closeService();
        sc.close();
        System.out.println("Program terminated.");
    }

    private static void insertEmployees(Scanner sc, empServices service) {
        ArrayList<Employee> employees = new ArrayList<>();
        System.out.print("Enter number of employees to add: ");
        int n = getValidIntInput(sc);

        for (int i = 0; i < n; i++) {
            System.out.println("\nEnter details for Employee " + (i + 1));
            String name = getValidStringInput(sc, "Name");
            int age = getValidIntInput(sc, "Age");
            String dept = getValidStringInput(sc, "Department");
            String location = getValidStringInput(sc, "Location");

            employees.add(new Employee(name, age, dept, location));
        }

        service.insertIntoTable(employees);
        System.out.println("Employees added successfully.");
    }

    private static void displayEmployees(List<Employee> employees) {
        if (employees.isEmpty()) {
            System.out.println("No employee records found.");
        } else {
            for (Employee e : employees) {
                System.out.println(e);
            }
        }
    }

    private static String getValidStringInput(Scanner sc, String field) {
        while (true) {
            System.out.print("Enter " + field + ": ");
            String input = sc.nextLine().trim();
            if (!input.isEmpty())
                return input;
            System.out.println(field + " cannot be empty. Try again.");
        }
    }

    private static int getValidIntInput(Scanner sc, String field) {
        while (true) {
            try {
                System.out.print("Enter " + field + ": ");
                return Integer.parseInt(sc.nextLine().trim());
            } catch (NumberFormatException e) {
                System.out.println("Invalid number. Try again.");
            }
        }
    }

    private static int getValidIntInput(Scanner sc) {
        return getValidIntInput(sc, "number");
    }
}
// javac -cp ".;mysql-connector-j-9.2.0.jar" *.java
// java -cp ".;mysql-connector-j-9.2.0.jar" MainClass