JA-VA

public class Car {
    private String registration;
    private int doors;
    private String colour;
    private CarDealer supplier;
    private static int totalCars = 0;
    public Car() {
        this.registration = null;
        this.doors = 0;
        this.colour = null;
        this.supplier = null;
        ++totalCars;
    }
    public Car(
            String registration,
            int doors,
            String colour,
            CarDealer supplier
    ){
        this.registration = registration;
        this.doors = doors;
        this.colour = colour;
        this.supplier = supplier;
        ++totalCars;
    }

    public static int getTotalCars() {
        return totalCars;
    }

    public static void setTotalCars(int totalCars) {
        Car.totalCars = totalCars;
    }

    public String getColour() {
        return colour;
    }

    public void setColour(String colour) {
        this.colour = colour;
    }

    public void setRegistration(String registration) {
        this.registration = registration;
    }

    public String getRegistration() {
        return registration;
    }

    public CarDealer getSupplier() {
        return supplier;
    }

    public void setSupplier(CarDealer supplier) {
        this.supplier = supplier;
    }
}