Concurrency without pain in Java

Synchronized makes one cross the memory barrier. Synchronizes local memory with remote memory.
Java Concurrency by ...
Use of Lock object for synchronization.
Software Transactional Memory makes everything immutable. Identity and state is separated. Identity is conditionally mutable ; enforces transaction before allowing mutation. Clojure supports STM.
Use of Clojure for simple Concurrency in Java.
Use LockingTransaction.runInTransaction.

Use Multiverse .