Java：从枚举中选择一个随机值？ [英] Java: Pick a random value from an enum?

问题描述

如果我有这样的枚举：

public enum Letter {
    A,
    B,
    C,
    //...
}

什么是随机选择一个最好的方法？它不需要生产质量防弹，但相当均匀的分布将是很好的。

What is the best way to pick one randomly? It doesn't need to be production quality bulletproof, but a fairly even distribution would be nice.

我可以做这样的事情

private Letter randomLetter() {
    int pick = new Random().nextInt(Letter.values().length);
    return Letter.values()[pick];
}

但是有更好的方法吗？我觉得这是以前解决的东西。

But is there a better way? I feel like this is something that's been solved before.

推荐答案

我建议的唯一的事情是缓存<$ c的结果$ c> values（）因为每个调用都复制一个数组。另外，不要每次都创建一个 Random 。保持一个除了你在做什么是好的。所以：

The only thing I would suggest is caching the result of values() because each call copies an array. Also, don't create a Random every time. Keep one. Other than that what you're doing is fine. So:

public enum Letter {
  A,
  B,
  C,
  //...

  private static final List<Letter> VALUES =
    Collections.unmodifiableList(Arrays.asList(values()));
  private static final int SIZE = VALUES.size();
  private static final Random RANDOM = new Random();

  public static Letter randomLetter()  {
    return VALUES.get(RANDOM.nextInt(SIZE));
  }
}

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