public class BuyCar {

    //instance variable, the Car to be bought!
    Car car;

    public void buy(String type) {

        if (type.equalsIgnoreCase("bentley")) {
            car = new Bentley();
        } else if (type.equalsIgnoreCase("ferrari")) {
            car = new Ferrari();
        } else {
            System.out.println("Invalid car type.");
            return;
        }

        System.out.println("Processing car purchase...");
        System.out.println(car.toString());
        car.drive();
    }
}