Java枚举与具有公共静态final字段的类有什么优势？ [英] What's the advantage of a Java enum versus a class with public static final fields?

问题描述

我非常熟悉C＃，但开始在Java中工作更多。我预计会了解Java中的枚举基本上与C＃中的枚举相似，但显然不是这样。最初我很高兴地知道，Java枚举可能包含多个数据，这似乎非常有利（ http://docs.oracle.com/javase/tutorial/java/javaOO/enum.html ）。然而，从那时起，我发现很多功能在C＃中是微不足道的，例如能够轻松地将枚举元素分配给某个值，因此能够将整数转换为枚举，而不需要相当的努力（即将整数值转换为匹配的Java Enum ）。

所以我的问题是：有一个公共静态最终字段的一个类的Java枚举有什么好处吗？还是只是提供更紧凑的语法？

编辑：让我更清楚。相同类型的一组公共静态最终字段的类的一个类的Java枚举有什么好处？例如，在第一个链接的行星示例中，枚举超过具有这些公共常量的类的优点：

  public static final Planet MERCURY = new Planet（3.303e + 23，2.4397e6）; 
 public static final Planet VENUS = new Planet（4.869e + 24，6.0518e6）; 
 public static final Planet EARTH = new Planet（5.976e + 24，6.37814e6）; 
 public static final Planet MARS = new Planet（6.421e + 23，3.3972e6）; 
 public static final Planet JUPITER = new Planet（1.9e + 27，7.1492e7）; 
 public static final Planet SATURN = new Planet（5.688e + 26，6.0268e7）; 
 public static final Planet URANUS = new Planet（8.686e + 25，2.5559e7）; 
 public static final行星NEPTUNE = new Planet（1.024e + 26，2.4746e7）; 
  

据我所知，casablanca的答案是唯一满足此要求的答案。

解决方案

技术上，可以将枚举视为具有一系列类型常量的类，这实际上是内部实现枚举常量。然而，使用枚举可以提供有用的方法（ c code code code code code code code code code code $ $ b

I am very familiar with C# but starting to work more in Java. I expected to learn that enums in Java were basically equivalent to those in C# but apparently this is not the case. Initially I was excited to learn that Java enums could contain multiple pieces of data which seems very advantageous (http://docs.oracle.com/javase/tutorial/java/javaOO/enum.html). However, since then I have found a lot of features missing that are trivial in C#, such as the ability to easily assign an enum element a certain value, and consequently the ability to convert an integer to an enum without a decent amount of effort (i.e. Convert integer value to matching Java Enum).

So my question is this: is there any benefit to Java enums over a class with a bunch of public static final fields? Or does it just provide more compact syntax?

EDIT: Let me be more clear. What is the benefit of Java enums over a class with a bunch of public static final fields of the same type? For example, in the planets example at the first link, what is the advantage of an enum over a class with these public constants:

public static final Planet MERCURY = new Planet(3.303e+23, 2.4397e6);
public static final Planet VENUS = new Planet(4.869e+24, 6.0518e6);
public static final Planet EARTH = new Planet(5.976e+24, 6.37814e6);
public static final Planet MARS = new Planet(6.421e+23, 3.3972e6);
public static final Planet JUPITER = new Planet(1.9e+27, 7.1492e7);
public static final Planet SATURN = new Planet(5.688e+26, 6.0268e7);
public static final Planet URANUS = new Planet(8.686e+25, 2.5559e7);
public static final Planet NEPTUNE = new Planet(1.024e+26, 2.4746e7);

As far as I can tell, casablanca's answer is the only one that satisfies this.

解决方案

Technically one could indeed view enums as a class with a bunch of typed constants, and this is in fact how enum constants are implemented internally. Using an enum however gives you useful methods (Enum javadoc) that you would otherwise have to implement yourself, such as Enum.valueOf.

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