在if语句中格式化多个'或'条件的最佳方法（Java） [英] Best way to format multiple 'or' conditions in an if statement (Java)

问题描述

一个简单的问题，但谷歌没有多少帮助。

A simple question but Google hasn't been helping much.

我有一个if语句有很多条件（必须检查10或15个常数，看看是否他们中的任何一个都在场。）

I have an if statement with many conditions (have to check for 10 or 15 constants to see if any of them are present.)

而不是写下这样的东西：

Instead of writing something like:

if (x == 12 || x == 16 || x == 19 || ...)

有没有办法格式化它像

if x is [12, 16, 19]?

只是想知道是否有更简单的方法对此进行编码，任何帮助都会受到赞赏。

Just wondering if there is an easier way to code this, any help appreciated.

编辑：答案非常有用，但有人要求我添加更多细节，以便满足他们的好奇心。我正在制作一个日期验证课程，需要确保在仅有30天的时间里天数不超过30天（其中有4天，我认为）并且我正在写一个if语句来检查这样的事情：

Edit: The answers have been very helpful, but I was asked to add more detail by a few people so I will do that to satiate their curiosity. I was making a date validation class that needed to make sure days were not > 30 in the months that have only 30 days (of which there are 4, I think) and I was writing an if statement to check things like this:

if (day > 30 && (month == 4 || month == 6 || month == 9 || month == 11))

我只是想知道是否有更快的方法来编写像 - 下面的许多答案都有帮助:)。

I was just wondering if there was a faster way to code things like that - many of the answers below have helped :).

推荐答案

我经常使用这种模式。它非常紧凑：

I use this kind of pattern often. It's very compact:

// Define a constant in your class. Use a HashSet for performance
private static final Set<Integer> values = new HashSet<Integer>(Arrays.asList(12, 16, 19));

// In your method:
if (values.contains(x)) {
    ...
}

这里使用 HashSet 来提供良好的查找性能 - 即使是非常大的哈希集能够非常快速地执行 contains（）。

A HashSet is used here to give good look-up performance - even very large hash sets are able to execute contains() extremely quickly.

如果性能不重要，你可以编写要点它分为一行：

If performance is not important, you can code the gist of it into one line:

if (Arrays.asList(12, 16, 19).contains(x))

但是知道它每次都会创建一个新的 ArrayList 它执行。

but know that it will create a new ArrayList every time it executes.

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