是有java.concurrent.util（或等效）为WeakHashMap？ [英] is there java.concurrent.util (or equivalent) for WeakHashMap?

问题描述

下面的代码可以使用 Collections.synchronizedMap（）重写，但是仍然保持并发的正确性？

  Collections.synchronizedMap（new WeakHashMap< Class，Object>（））; 
  

是否有来自java.util.concurrent的东西可以改用？注意，只需用

  new ConcurrentHashMap< Class，Object>（new WeakHashMap< Class，Object> 
  

显然不会工作

解决方案

Guava 的 CacheBuilder 类允许

  CacheBuilder.newBuilder（）。weakKeys（）。build（）
  == ，而不是<$  c $ c> .equals（）这在您使用 Class 实例时并不重要，但是是一个潜在的陷阱。
 
Can the following piece of code be rewritten w/o using Collections.synchronizedMap() yet maintaining correctness at concurrency? 
Collections.synchronizedMap(new WeakHashMap<Class, Object>());
i.e. is there something from java.util.concurrent one can use instead? Note that merely replacing with 
new ConcurrentHashMap<Class, Object>(new WeakHashMap<Class, Object>()));
obviously won't work
解决方案
Guava's CacheBuilder class allows you to do this easily.
CacheBuilder.newBuilder().weakKeys().build()
Note that this changes key equality semantics to be == instead of .equals() which will not matter in your case of using Class instances but is a potential pitfall.

                        
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