Java multi-threading atomic reference assignment

Question

I have a cache which I implemented using a simeple HashMap. like -

HashMap cache = new HashMap();

Answer 1

What about CopyOnWrite.. collections:

java.util.concurrent.CopyOnWriteArraySet
java.util.concurrent.CopyOnWriteArraySet
and org.apache.mina.util.CopyOnWriteMap

They can be a good match in your case and they are thread-safe.