is there java.concurrent.util (or equivalent) for WeakHashMap?

Question

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

Answer 1

You could use a ConcurrentHashMap<Class, WeakReference<Object>>, but you'd need to write additional boilerplate code to read and write from the data structure.

Answer 2

I don't believe there is. In fact the javadoc suggests using Collections.synchronizedMap()

"Like most collection classes, this class is not synchronized. A synchronized WeakHashMap may be constructed using the Collections.synchronizedMap method."

Answer 3

Google Collections' MapMaker class allows you to do this easily. Check it out, the project is awesome...