When should I use a Hashtable versus a HashMap

Question

This is not a question about the differences between Hashtable and HashMap. I understand that a Hashtable object cannot accept

Answer 1

I only see Hashtables in legacy apps/ libraries.

If you can, use ConcurrentHashMap or Collections.synchronizedMap if you need a synchronized Map.

http://docs.oracle.com/javase/7/docs/api/java/util/concurrent/ConcurrentHashMap.html

http://docs.oracle.com/javase/7/docs/api/java/util/Collections.html#synchronizedMap%28java.util.Map%29