// Entity class for booking
    
public class Booking {
        
        private int distance;
        private static int bookingId = 1000;
        private int cabId;
        private int customerId;
        private int billingAmount;
        
        public Booking() {
            
            bookingId++;
            System.out.println(bookingId);
            
        }
}
    
// Service class for booking, I'm setting up all parameters here.
        
public class BookCab {
    
        public Booking bookCab(int distance, int customerId){
            Booking book = new Booking();
            
            CabDao cabDao = new CabDaoImpl();
            
            book.setDistance(distance);
            book.setCustomerId(customerId);
            
            book.setCabId(cabDao.getCabId()); //retrieving cab data from database
            
            if(distance>10) {book.setBillingAmount(305 + (distance-10)*25);}
            else if (distance <10 & distance>5) {
                
                book.setBillingAmount(180 + (distance-5)*25);
            }
            else if (distance <5 & distance>1) {
                
                book.setBillingAmount(100 + (distance-1)*20);
            }
            else    book.setBillingAmount(100);
            
            return book;
        }
}
    
// This is DAO Implementation for accessing the Database.
    
public class BookingDaoImpl implements BookingDao {

    Connection connection = null;
    PreparedStatement ptmt = null;
    ResultSet resultSet = null;
    
    public BookingDaoImpl() {};
    
    private Connection getConnection() throws SQLException {
        Connection conn;
        conn = DbUtil.getInstance().getConnection();
        return conn;
    }
    
    public void addBooking(Booking booking) {
        
        try {
            String queryString = "INSERT INTO Booking(bookingId, customerId, cabId, distance, chargingAmount) VALUES(?,?,?,?,?)";
            connection = getConnection();
            ptmt = connection.prepareStatement(queryString);
            ptmt.setInt(1, booking.getBookingId());
            ptmt.setInt(2, booking.getCustomerId());
            ptmt.setInt(3, booking.getCabId());
            ptmt.setInt(4, booking.getDistance());
            ptmt.setInt(5, booking.getBillingAmount());
            ptmt.executeUpdate();
            System.out.println("Data Added Successfully");
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            try {
                if (ptmt != null)
                    ptmt.close();
                if (connection != null)
                    connection.close();
            } catch (SQLException e) {
                e.printStackTrace();
            } catch (Exception e) {
                e.printStackTrace();
            }

        }
    }
}
    
// Driver class
    
public class MainView {

    public static void main(String[] args) {
    
        BookCab bookCab = new BookCab();
        
        BookingDao bookingDao = new BookingDaoImpl();
        bookingDao.addBooking(bookCab.bookCab(16, 691744));
        
    }
}
    
/* Output 
        
        1001
        Data Added Successfully
        
        1001
        Data Added Successfully
        
        1001
        Data Added Successfully
  */

The counter is not working, booking id is not incremented.

I've tried printing counter right after incrementing, but it's the same there as well.