Code Talk

There are several differences between HashMap and Hashtable in Java: Hashtable  is synchronized, whereas  HashMap  is not. This makes  HashMap  better for non-threaded applications, as unsynchronized Objects typically perform better than synchronized ones. Hashtable  does not allow null keys or values.  HashMap  allows one null key and any number of null  values. One of HashMap's subclasses is  LinkedHashMap , so in the event that you'd want predictable iteration order (which is insertion order by default), you could easily swap out the  HashMap  for a  LinkedHashMap . This wouldn't be as easy if you were using  Hashtable . Since synchronization is not an issue for you, I'd recommend  HashMap . If synchronization becomes an issue, you may also look at  ConcurrentHashMap .