[OCPJP]final的類別與方法

Given:

public final class IceCream {

    public void prepare() {
    }
}

public class Cake {

    public final void bake(int min, int temp) {
    }

    public void mix() {
    }
}

public class Shop {

    private Cake c = new Cake();
    private final double discount = 0.25;

    public void makeReady() {
        c.bake(10, 120);
    }
}

public class Bread extends Cake {

    public void bake(int minutes, int temperature) {
    }

    public void addToppings() {
    }
}

Which statement is true?

A. A compilation error occurs in IceCream.
B. A compilation error occurs in Cake.
C. A compilation error occurs in Shop.
D. A compilation error occurs in Bread
E. All classes compile successfully.

題解

Bread.java第三行的bake方法會編譯錯誤，因為Bread類別繼承的Cake類別，其bake方法已經使用了final來修飾，無法被覆寫。