使用集合时出错。使用ArrayList和类排序（）。（爪哇）

Question

实际上，我正在尝试使用外部排序来排序ArrayList（我知道这比这个简单，但我的老师希望这样）

我有下一个代码：

//MainClass

    public static void main(String[] args) {
        Cotxe coche1 = new Car("Opel","Corsa",200);
        Cotxe coche2 = new Car ("Ferrari","Italia",200);
        Cotxe coche3 = new Car ("Porsche","Cayenne",200);

        ArrayList<Car> list = new ArrayList<Car>();

        list.add(car1);
        list.add(car2);

        Collections.sort(list, new OrderCarByModel());
    }

//COMPARATOR CLASS

public interface Comparator <Car>{
    int compare(Car c1, Car c2);
    boolean equals(Object obj);
}

//ORDERCARBYMODEL CLASS

public class OrderCarByModel implements Comparator<Car> {
    @Override
    public int compare(Car c1, Car c2) {
        return c1.getModel().compareTo(c2.getModel());
    }

//CAR CLASS ONLY HAVE 3 ATTRIBUTES. BRAND, MODEL AND PRICE, IT'S A PRETTY SIMPLE CLASS.

错误出现在“Collections.sort（list，new OrderCarByModel（））；”中在主课上

Sorry for the translation, I just translated the code in the post but not in the error picture, "Cotxe" means "Car" and "OrdenarCocheModelo" means "OrderCarByModel".