定义真，假，未设定状态的最佳方法 [英] Best way to define true, false, unset state

问题描述

如果你有，你需要知道在哪里没有设置一个布尔值（例如，如果该取消设置值应该从父继承值）在Java布尔原语（和其它语言的相当值）的情况显然是不足够了。

什么是实现这一目标的最佳做法？定义一个新的简单的类，它能够EX pressing全部三种状态，或者使用Java Boolean类和使用null表示未设定状态？

解决方案

 一个Boolean = TRUE;
布尔B = FALSE;
布尔C = NULL;
 

我会使用它。这是最直接的。

另一种方法是使用一个枚举。也许这就是更好，更快，因为不需要拳击：

 公共枚举三态{
    真正，
    假，
    TRALSE
};
 

有是第一的优势，你的类的用户并不需要关心你的三态布尔值。他们还可以通过真正和假。如果你不喜欢空，因为它告诉，而一些关于它的意义在这里，你仍然可以做一个公共静态最终布尔tralse = NULL ; 在你的类

。

If you have a situation where you need to know where a boolean value wasn't set (for example if that unset value should inherit from a parent value) the Java boolean primitive (and the equivalent in other languages) is clearly not adequate.

What's the best practice to achieve this? Define a new simple class that is capable of expressing all three states or use the Java Boolean class and use null to indicate the unset state?

解决方案

Boolean a = true;
Boolean b = false;
Boolean c = null;

I would use that. It's the most straight-forward.

Another way is to use an enumeration. Maybe that's even better and faster, since no boxing is required:

public enum ThreeState {
    TRUE,
    FALSE,
    TRALSE
};

There is the advantage of the first that users of your class doesn't need to care about your three-state boolean. They can still pass true and false. If you don't like the null, since it's telling rather little about its meaning here, you can still make a public static final Boolean tralse = null; in your class.

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