Comments (2)
疑问的文章:https://github.com/MarsonShine/Books/blob/master/ThinkingInJava/docs/enumerated.md
问题:我认为文章中这部分意思传达错误:
//以下是尝试把枚举项传参 //是不允许这样的 class NotPromise { void method(LikesClass.ITEM1 instance){} }
原文是“同样,在 Java 中枚举中的项是不能像 C# 中枚举一样可以在方法中当作参数传递的”
观点:在C#中也不能这样传递,我已经动手试过来了。 JAVA的枚举本质上是类,C#的枚举本质是一种特殊的简单
struct
。两者的区别是在设计和实现上的区别,在业务信息传达
上面却是一样的
很抱歉才看到这个issue,的确是这样的。之前对java 枚举的理解有误。
如果在 java enum 申明一个变量,这个变量其实也是 static 的。
很显然下面的这种写法很让人困惑:
enum LikesClass {
ITEM1 { void action(){ print("action1");}},
ITEM2 { void action(){
print("action2");
state = 2;
}},
ITEM3 { void action(){ print("action3");}};
abstract void action();
int state = 0;
}
... main
LikesClass instance = LikesClass.ITEM2;
instance.action();
print(instance.state); // 这里的 state 变量到底是实例化变量还是静态变量?
就像上面的注释一下,实际上 java 是不允许这么写的:LikesClass.state。然后就想当然的做了文章后续的判断。
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恩恩, JAJVA我了解的很少,C#里的枚举能肯定是静态的,JAVA我就不清楚了。 有可能他是一个枚举类,然后做了处理,让这个类new一个并静态化,静态的是类的引用,也能达到这样的效果
from books.
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