有没有办法在 Java 中按位或枚举？
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Is there a way to bitwise-OR enums in Java?
提问by Yet Another Geek
I'm using a state machine, and the code's getting really verbose when testing against a large number of possible states.
我正在使用状态机，并且在针对大量可能的状态进行测试时，代码变得非常冗长。
enum Mood {
HAPPY, SAD, CALM, SLEEPY, OPTIMISTIC, PENSIVE, ENERGETIC;
}
Is there any way to do this:
有没有办法做到这一点：
if (currentMood == (HAPPY | OPTIMISTIC | ENERGETIC) {}
Instead of this:
取而代之的是：
if (currentMood == HAPPY || currentMood == OPTIMISTIC || currentMood == ENERGETIC) {}
Or would it be better to stick with integers and flags in this case?
或者在这种情况下坚持使用整数和标志会更好吗？
回答by Yet Another Geek
回答by Mario Marinato
Give your enums an int attribute.
给你的枚举一个 int 属性。
enum Mood {
private int id;
HAPPY(1), SAD(2), CALM(4), SLEEPY(8), OPTIMISTIC(16), PENSIVE(32), ENERGETIC(64);
Mood( int id ) {
this.id = id;
}
}
On the if, test against this atrribute.
在 if 上，针对此属性进行测试。
if ( currentMood & ( HAPPY.id | OPTIMISTIC.id | ENERGETIC.id ) != 0 ) { ... }
回答by leonbloy
Apart from other answers: if that particular set of states has a semantically defined meaning in your application (rather independent of your particular method, specific to the Enum) , I'd recommend to included that test as a method in the same Enum class.
除了其他答案：如果该特定状态集在您的应用程序中具有语义定义的含义（而不是独立于您的特定方法，特定于 Enum），我建议将该测试作为方法包含在同一个 Enum 类中。
enum Mood {
HAPPY, SAD...
public boolean isRatherPositive() {
....
}
}
(or a static method) to be implemented by any of the logic suggested by the other answers (I'd favour the EnumSet, which could be statically o lazily instantiated).
（或静态方法）由其他答案建议的任何逻辑实现（我更喜欢 EnumSet，它可以静态地 o 懒惰地实例化）。
To have the method in the Enum is useful to avoid code duplication, but above all, to prevent bugs in case you add members to the Enum or modify it.
在 Enum 中使用该方法有助于避免代码重复，但最重要的是，可以防止在向 Enum 添加成员或修改它时出现错误。
回答by Stas Jaro
Yes
是的
switch(currentmood){
case HAPPY:
case OPTIMISTIC:...
Then do this
break;
default://else
}
回答by josefx
You could give your enum a boolean flag and test for that.
你可以给你的枚举一个布尔标志并测试它。
enum Mood {
HAPPY(true), SAD, CALM, SLEEPY, OPTIMISTIC(true), PENSIVE, ENERGETIC(true);
final boolean good;
Mood(){this(false);}
Mood(boolean isgood){this.good = isgood;}
public isGood(){return good;}
}
This way the check is short
这样支票很短
if (currentMood.isGood()) {}
回答by Dilum Ranatunga
One approach is to have EnumSet/switch/if etc. This makes sense if you are classifying the enumeration in some way that is not intrinsically part of the enumeration itself. For example, whether a color is part of the national flag's color. The 'dependency model' is that national flag depends on Color, but Color doesn't care about the existence of national flags.
一种方法是使用 EnumSet/switch/if 等。如果您以某种方式对枚举进行分类，而这本身并不是枚举本身的一部分，那么这很有意义。例如，颜色是否是国旗颜色的一部分。“依赖模型”是国旗取决于颜色，但颜色并不关心国旗的存在。
On the other hand, if you are trying to determine whether a color is a primary color or not (intrinsic to human model of color), then it belongs on the enum class itself. So,
另一方面，如果您试图确定一种颜色是否是原色（人类颜色模型所固有的），那么它属于枚举类本身。所以，
enum Color {
private final boolean _crtPrimary;
Red(true), Green(true), Blue(true), Black(false)
Color(boolean crtPrimary) {
_crtPrimary = crtPrimary;
}
public boolean isCRTPrimary() {
return _crtPrimary;
}
}
回答by Roy Doron
You can use YourEnum.values()
您可以使用 YourEnum。值（）
For example, I have Class called Enumerations. In it, I have multiple Enum Classes.
例如，我有一个名为Enumerations 的类。在其中，我有多个 Enum 类。
For example:
例如：
public class Enumerations {
public enum smtg
{
Fast(1),
Slow(2);
private int number;
private smtg(final int num) { number = num; }
public int getsmtg()
{
return number;
}
}
......
}
}
When I want to use bitwise, I just use it like that:
当我想按位使用时，我只是这样使用它：
Enumerations.smtg.values()[Enumerations.smtg.Slow.ordinal() | Enumerations.smtg.Fast.ordinal()]
回答by Hunter McMillen
When you use || you have to specify both values you are comparing each time. You could easily write a small method to do this though.
当你使用 || 您必须指定每次比较的两个值。不过，您可以轻松编写一个小方法来执行此操作。
if (currentMood.hasMood(HAPPY, OPTIMISTIC, ENERGETIC)) {}
public boolean hasMood(Mood ....)
回答by ejaenv
Another option:
另外一个选择：
public enum PaymentResponse {
PP_SUCCESS, PP_FAILURE, CC_SUCCESS, CC_FAILURE;
public boolean isSuccessful() {
return ordinal() == CC_SUCCESS.ordinal() ||
ordinal() == PP_SUCCESS.ordinal() ;
}
}
