Java 枚举属性最佳实践
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Java Enum property best practice
提问by JustinKSU
I've seen two approaches to handling enums with properties. Is one better than the other?
我见过两种处理带有属性的枚举的方法。这个比那个好吗？
As a property:
作为财产：
public enum SEARCH_ENGINE {
GOOGLE("http://www.google.com"),
BING("http://www.bing.com");
private final String url;
private SEARCH_ENGINE(String url) {
this.url = url;
}
public String getURL() {
return url;
}
}
As a method:
作为一种方法：
public enum SEARCH_ENGINE {
GOOGLE {
public String getURL() {return "http://www.google.com";}
},
BING {
public String getURL() {return "http://www.bing.com";}
};
public abstract String getURL();
}
回答by Jon Skeet
The first clearly looks cleaner to me - it makes use of the commonality that each element of the enum will have a fixed String URL which is known at initialization. You're effectively repeating that "logic" in each implementation in the second version. You're overriding a method to provide the same logic("just return a string which is known at compile-time") in each case. I prefer to reserve overriding for changes in behaviour.
第一个显然对我来说看起来更清晰 - 它利用了枚举的每个元素都有一个固定的字符串 URL 的共性，该 URL 在初始化时是已知的。您在第二个版本的每个实现中有效地重复了该“逻辑”。在每种情况下，您都覆盖了一个方法以提供相同的逻辑（“只返回一个在编译时已知的字符串”）。我更喜欢保留覆盖行为的变化。
I suggest making the urlfield private though, in the first.
url不过，我建议首先将该领域设为私有。
回答by John Kane
Take a look at item 21 from this chapter of Josh Bloch's Effective Java. It talks about the type safe enum pattern.
查看Josh Bloch 的 Effective Java本章中的第21 项。它讨论了类型安全的枚举模式。
回答by DerMike
I'd go with the first since the compiler complains if you somehow forget to add a url. The second would let you make errors here.
如果您以某种方式忘记添加 url，我会选择第一个，因为编译器会抱怨。第二个会让你在这里犯错误。
