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Hashtable vs HashMap

Ronnie Ho
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Joined: Aug 10, 2005
Posts: 47

What is the major difference between a hashtable and hashmap? Thanks.
Seb Mathe
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Joined: Sep 28, 2005
Posts: 225
Hashtable is synchronized, HashMap not.

Regards,<br />Seb<br /> <br />SCJP 1.4
Amar Shrivastava

Joined: Oct 17, 2005
Posts: 13
HashMap class is not thread-safe nad permits one null key,the HashTable class is thread-safe and permits non-null keys and values only.
The Thread-safety that <i>HashTable</i> class provides has a performance penalty. HashTable class is a legay class that has been retrofitted to implement the Map interface.
Jeff Albertson
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Joined: Sep 16, 2005
Posts: 1780
if you are considering using HashTable or Collections.synchronizedMap(new HashMap())
because its methods are "thread-safe", check out java.util.concurrent.ConcurrentHashMap first:

Brian Goetz's articl on ConcurrentHashMap

ConcurrentHashMap API

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Ronnie Ho
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Joined: Aug 10, 2005
Posts: 47
Thanks all.
I agree. Here's the link:
subject: Hashtable vs HashMap
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