How do I pass an object created in one class to another in java?

Question

I\'m trying to develop an online hotel booking system. I have the main class which takes input from the user such as their name, their payment information, and other data field

Answer 1

I believe you must have tried this

public void addReservation(Reservation reservation)
{
    reservations.add(reservation);
}

but the problem here is that your list reservations is null and will throw null pointer exception. So better initialize it at declaration. So change this

private ArrayList reservations;

to

private ArrayList reservations = new ArrayList();

And in your makeReservation method of Hotel class do this:

Room room = new Room();
room.addReservation(reservation);