如何将私有 int 类型字段的值加倍？

Question

这是类Enemy中方法takeDamage的代码，它是类Vampire的超类。

public void takeDamage(int damage) {
    int remainingHitPoints = hitPoints - damage;

    if (remainingHitPoints > 0) {
        setHitPoints(remainingHitPoints);
        System.out.println(name + " took " + damage + " damage and have " + remainingHitPoints + " HitPoint left" + "\n------------------------------------" );
    } else {
        this.lives = this.lives - 1;
        System.out.println(name + " took " + damage + " damage" + "\n------------------------------------" + "\n" + name +" lost a life" + "\n------------------------------------");

        if (lives > 0) {
            System.out.println(name + " revived" + "\n------------------------------------");
            setHitPoints(remainingHitPoints + damage);
        } else {
            System.out.println(name + " is dead now RIP" + "\n------------------------------------");
            setHitPoints(0);
        }
    }
}

在Vampire 类中，我重写了takeDamge 方法：

public void takeDamage(int damage) {
    int inflictedDamage = damage/2;
    int doubleHitPoints = getHitPoints()*2;
    int remainingHitPoints = getHitPoints() - inflictedDamage;
    int remainingLives = getLives() - 1;

    if (remainingHitPoints > 0) {
        setHitPoints(remainingHitPoints);
        System.out.println(getName() + " took " + inflictedDamage + " damage(Vampire takes inflicted damage) and has " + remainingHitPoints + " HitPoint left" + "\n------------------------------------" );
    } else {
        setLives(remainingLives);
        System.out.println(getName() + " took " + inflictedDamage + " damage(Vampire takes inflicted damage)" + "\n------------------------------------" + "\n" + getName() +" lost a life" + "\n------------------------------------");

        if (remainingLives > 0) {
            System.out.println(getName() + " revived and even got stronger!" + "\n------------------------------------");
            setHitPoints(doubleHitPoints);
        } else {
            System.out.println(getName() + " is dead now RIP" + "\n------------------------------------");
            setHitPoints(0);
        }
    }
}

我打算将对象的 hitPoints 加倍，它最初由构造函数设置。

当Vampire 对象受到足够的伤害而死时（换句话说，当它失去生命时），此方法成功地将对象的hitPoints 加倍。

当Vampire 对象受到的伤害不足以导致死亡时，问题就会发生（如果我诊断正确的话）。

setHitPoints(remainingHitpoints); 被执行，当Vampire 对象受到足够多的伤害而死时，它会将对象的remainingHitPoints 翻倍，而不是原来的hitPoints。

我想解决这个问题。

hitPoints 字段在Enemy 类中被声明为私有，所以如果我理解得很好，修改该字段值的唯一方法是在getHitPoint 类中使用getHitPoint 方法（getter） .

Answer 1

你需要一个存储原始生命值的地方。

如果您的 Enemy 类没有提供此信息，而您只需要在 Vampire 类中使用它，您可以按照以下方式更改 Vampire 类：

public class Vampire extends Enemy {

    private int originalHitPoints;

    public Vampire() {
        // ...
        originalHitPoints = getHitPoints();
    }

    public void takeDamage(int damage) {
        // ...

        if (remainingLives > 0) {
            System.out.println(getName() + " revived and even got stronger!" + "\n------------------------------------");
            setHitPoints(originalHitPoints * 2);
        }

        // ...
    }
}

如果你想在每次吸血鬼死亡时将生命值加倍，你可以像这样更改takeDamage() 的代码：

    public void takeDamage(int damage) {
        // ...

        if (remainingLives > 0) {
            System.out.println(getName() + " revived and even got stronger!" + "\n------------------------------------");
            originalHitPointes *= 2; // double the hit points
            setHitPoints(originalHitPoints);
        }

        // ...
    }