what's the difference between hashtable and hashMap

[rose deng]

Hi,
Could anybody tell me what's the difference between hashtable and hashMap, when should i use hashMap, not hashtable.
Thanks a lot.

[John Smith]

Hashtable is synchronized and HashMap is not. I believe that is the only difference. Use Hashtable if you need thread-safety. Otherwise, use HashMap since it should be somewhat faster since there's no synchronization.

[Blake Minghelli]

A HashMap also permits a null key

[Thomas Paul]

Actually you should never use Hashtable. If you need a synchronized HashMap then use:
Map syncMap = Collections.synchronizedMap(myMap);

[John Smith]

Just curious; why should Hashtable never be used?
Randy

[Ron Newman]

Hashtable, Vector, and Stack are old classes that predate the 1.2 Collections framework.
I guess they haven't been formally deprecated, but Sun recommends that new code use HashMap and ArrayList instead.
And generally, once you create a HashMap, you should store it in a Map variable, and use Map rather than HashMap arguments to methods. This way, you could someday substitute a TreeMap or some other Map easily without changing much code.