在枚举中查找最大值

Question

我正在为我正在制作的游戏制作课程，但不知道如何将最高“奖励”返还给用户：

我想让它做的是根据玩家的击杀数返还奖励。如果他有 38 次击杀，它应该只返回 300。而不是 150。

    class EnumTest {

private static int playerKills = 38;

private enum KillReward {

    BEGINNER(10, 150),
    JUNIOR(25, 300),
    EXPERT(50, 500),
    CHAMPION(100, 1000);

    private KillReward(int kills, int reward) {
        this.kills = kills;
        this.reward = reward;
    }

    private int kills, reward;

    private int getKillsNeeded() {
        return kills;
    }

    private int getKillReward() {
        return reward;
    }
}

public static void main (String[] args) {
    for (KillReward k : KillReward.values()) {
        if (playerKills > k.getKillsNeeded()) {
            System.out.println("Kills: " + playerKills + "; Reward: " + k.getKillReward());
        }
    }
}

}

Answer 1

有几种方法可以做到这一点。

一种简单的方法是将奖励分配给一个变量。在该循环结束时，下面的reward 变量将是适用的最高击杀奖励

public static void main (String[] args) {
    KillReward reward = null;
    for (KillReward k : KillReward.values()) {
        if (playerKills > k.getKillsNeeded()) {
            reward = k;
        }
    }
    System.out.println("Kills: " + playerKills + "; Reward: " + k.getKillReward());
}

请注意，这依赖于按顺序列出的枚举，有时可能很脆弱。例如，如果在 CHAMPION 之后添加了一个新的 KillReward 枚举，但它的 killsNeeded 值较低，则它不会返回正确的值。

更好的解决方案是创建一个 Comparator 并使用它首先按 killsNeeded 对枚举值进行排序，从而确保它们始终按顺序排列。如果您还按降序对其进行排序，那么您也可以在点击第一个适用的循环后中断循环。

class EnumTest {

    private enum KillReward {

        BEGINNER(10, 150), JUNIOR(25, 300), EXPERT(50, 500), CHAMPION(100, 1000);

        // Sort KillRewards once at initialization
        private static final List<KillReward> sortedKillRewards = new ArrayList<KillReward>();
        static {
            for (KillReward k : values())
                sortedKillRewards.add(k);
            Collections.sort(sortedKillRewards, new Comparator<KillReward>() {
                @Override
                public int compare(KillReward o1, KillReward o2) {
                    return (o1.kills - o2.kills) * -1; // multiplying by -1 makes it
                    // descending
                }
            });
        }

        private KillReward(int kills, int reward) {
            this.kills = kills;
            this.reward = reward;
        }

        private int kills, reward;

        private int getKillsNeeded() {
            return kills;
        }

        private int getKillReward() {
            return reward;
        }

        public static KillReward forKills(int killCount) {
            for (KillReward k : sortedKillRewards)
                if (killCount >= k.kills)
                    return k;

            // must not have enough kills for any reward
            return null;
        }
    }

    public static void main(String[] args) {
        int kills = 9;
        System.out.println("Kills: " + kills + "; Reward: "
                + KillReward.forKills(kills));

        kills = 10;
        System.out.println("Kills: " + kills + "; Reward: "
                + KillReward.forKills(kills));

        kills = 38;
        System.out.println("Kills: " + kills + "; Reward: "
                + KillReward.forKills(kills));
    }

}