抽象泛型类中的静态变量 [英] Static variable in an abstract generic class

问题描述

我有一个称为缓存的类.它是一个通用的抽象类，负责为永远的类型处理全局缓存扩展了该类.我的问题是，如果我在基类下有一个静态变量，则该静态变量在每个扩展类型中是唯一的，还是对于所有扩展Cache的类型而言都是相同的.

I have a class called cache. It is an generic, abstract class responsible for handling the global cache for forever type extends the class. My question is, if I have a static variable under the base class, will the static variable be unique per extending type or will it be the same for all types that extend Cache.

例如界面:

Cache<K, V> 
  private static Cache<K, V>
  [creates a cache store on first load]
  static V get(K key);

然后我有一个实现类:

PersonCache extends Cache<String, Person>
   void load(String person);

JobCache extends Cache<Integer, Job>
   void load(Integer key);

应该从Cache的静态变量中获得哪种行为.[get变量的目的是成为JobCache/PersonCache的存储的单个公共入口点]每个类型(PersonCache，JobCache)是否都有自己的缓存存储，还是Cache会尝试存储接收到的所有内容?

Which behavior will be expected from Cache's static variable. [The get variable's intention is to be a single public entry point to the JobCache/PersonCache's store] will each type (PersonCache, JobCache] have its own cache store, or will Cache try to store everything it receives?

推荐答案

我认为您无法做到这一点.摘自 Java语言规范部分.8.1.2 :

I don't think you can do that. From the Java Language Specification Sec. 8.1.2:

在C的静态成员的声明或C中嵌套的任何类型声明的静态成员的声明中的任何地方引用C类的类型参数是编译时错误.引用C的静态初始化程序中的类C的类型参数或嵌套在C中的任何类的时间错误.

It is a compile-time error to refer to a type parameter of a class C anywhere in the declaration of a static member of C or the declaration of a static member of any type declaration nested within C. It is a compile-time error to refer to a type parameter of a class C within a static initializer of C or any class nested within C.

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