将类添加到 ArrayList 集合

Question

I'm currently working on an assignment where it's asking me to modify my previous method. My current method is:

public ParkingTicket issueParkingTicket(ParkedCar car,ParkingMeter meter){
    if(isParkingTimeExpired(car,meter) == true){
        ParkingTicket ticket = new ParkingTicket(getOfficerName(),getBadgeNumber(),car.getLicenseNumber(),car.getCarMake(),car.getCarModel(),calculateFine(car, meter));
        ticket.displayTicketDetails();
        return ticket;
    }
    return null;
}

The collection is a collection of parking tickets (which is also a class "public class ParkingTicket). The method I wrote above resides in a different class (public class ParkingOfficer).

This method will create an object. Additionally I'd like this method to create the object and add it to the collection as an ArrayList. How would I do that?

Answer 1

In your other class, do something like this:

ParkingTicket blah;
ParkingTicket foo;
ParkingTicket bar;

ArrayList<ParkingTicket> allDaTickets = new ArrayList<>();
allDaTickets.add(blah);
allDaTickets.add(foo);
allDaTickets.add(bar);

Answer 2

To Create an ArrayList of a certain class, you do: for example using the class 'Fruit' and calling the list 'fruits'.

List<Fruit> fruits = new ArrayList<>();

//to add an instance, to the above list, you use the add method
fruits.add(instance);

In your case, to create a list of ParkingTickets, it would be:

List<ParkingTicket> tickets = new ArrayList<>();
tickets.add(ticket); //ticket being an instance of ParkingTicket ofcourse

That being said, you code needs some refactoring. Your if condition should not be:

if(isParkingTimeExpired(car,meter) == true)

I'm assuming isParkingTimeExpired(car, meter) method already returns a boolean, so there is no need for the '==true' part in your condition checking. It would become something like this.

if(isParkingTimeExpired(car,meter)) { .... }

if the method returns true, it executes the block of the if statement.