What are the differences between a HashMap and a Hashtable in Java?

Question

What are the differences between a HashMap and a Hashtable in Java?

Which is more efficient for non-threaded applications?

Answer 1

My small contribution :

1. First and most significant different between Hashtable and HashMap is that, HashMap is not thread-safe while Hashtable is a thread-safe collection.

2. Second important difference between Hashtable and HashMap is performance, since HashMap is not synchronized it perform better than Hashtable.

3. Third difference on Hashtable vs HashMap is that Hashtable is obsolete class and you should be using ConcurrentHashMap in place of Hashtable in Java.