java枚举混淆
我遇到了以下java代码。这里接口包含两个方法，其中只有一个方法在枚举中实现。据说name()是自动实现的。我的问题是这怎么可能？我之前没有读过任何关于枚举中自动方法实现的规则。那么这里发生了什么？此外，代码没有给出任何类型的编译时错误。
interface Named {
public String name();
public int order();
}
enum Planets implements Named {
Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune;
// name() is implemented automagically.
public int order() { return ordinal()+1; }
}
I came across the following java code. Here interface contains two methods out of which only one method is implemented in the enum. It is written that name() is implemented automatically. My question is how is it possible? I have not read any rule regarding automatic method implementation in enum before. So what is happening here? Furthermore the code is not giving any type of compile time error.
interface Named {
public String name();
public int order();
}
enum Planets implements Named {
Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune;
// name() is implemented automagically.
public int order() { return ordinal()+1; }
}
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评论（5）
名称( )在 Enum 类中定义，它满足您的接口约定，因此您不必定义name()，除非您想覆盖默认行为。name()is defined in Enum class which satisfies your interface contract so you don't have to definename()unless of course you want to override the default behavior.enum有一个默认方法name()，仅此而已。它以及其他类似
values()、valueOf()和ordinal()来自 Enum 类。enumhas a default methodname(), that's all.It, and others like
values(),valueOf(), andordinal(), come from the Enum class.Java 中的所有枚举都隐式扩展 Enum，它实现了
name()方法。All enums in Java implicitly extend Enum, which implements the
name()method.在Java中，有一些为类型预先定义的属性和方法。对于枚举，方法
name()和对于数组，属性length都是示例。在您的示例中，方法 name() 将返回“Mercury”、“Venus”、“Earth”等。In Java, there are attributes and methods which are pre-defined for types. For enums, the method
name()and for arrays, the attributelengthare examples. In your example, the method name() would return "Mercury", "Venus", "Earth" and so on.每个
enum都派生自抽象类Enum。该类实现了name()和提到的ordinal()等等。看看吧。Every
enumis dervided from the abstract classEnum<E....>. That class implements bothname()and the mentionedordinal()and some more. Take a look.