Question

请允许我说,我有一个具有多重价值观的论坛,例如:

public enum Category {
  A, B, C, D;
}

并且希望建立一个锁定机制,以便我们只在一个时间处理一个类别的项目。我的第一个想法就是这样做:

Set categories = new HashSet();
for (Category cat : Category.values() {
  categories.put(cat);
}

在我需要获得一锁的时候,我做了以下工作:

synchronized(categories.get(category)) {
  ....
}

will this work or are all references to an enum value global so if some other thread, elsewhere, did the same thing they would block each other?

感谢!

Answer 1

Each enum value is a singleton. Only one instance exists for the classloader which loaded the enum class. So yes, if two threads use an enum value as a lock, they will use the same lock and thus block each other.

附带说明:如果你有效,汇编 Java,你的问题就会更清楚。

Answer 2

只有一个<代码>。 “ instance, so all synchronized (Category.A) will block each other, which is what You are do with You set.

您可使用与您有关的私人定本EnumMap,将其填入new Object(>,确保你不修改地图,并将与这一类有关的物体用作该类的锁。这样,你就可以确信,这一锁只用于该法典。

Answer 3

Your enum will be visible in your project (package). If you need to use this logick elsewhere, you will need to add reference to this project.

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