synchronized is not a class property. It is only applicable to methods and blocks. Following are the few implementations which can be safely used in multi-threaded environment:
- Vector
- Hashtable
- Stack
- ConcurrentHashMap
- SynchronizedHashMap
- CopyOnWriteArrayList
- CopyOnWriteArraySet
You can get a synchronized version of a Java Collection with
Collections.synchronizedCollection(Collection<T> c)