Re: synchronized HashMap vs. HashTable

From:
Knute Johnson <nospam@rabbitbrush.frazmtn.com>
Newsgroups:
comp.lang.java.programmer
Date:
Wed, 21 May 2008 15:28:24 -0700
Message-ID:
<4834a208$0$4049$b9f67a60@news.newsdemon.com>
Mikhail Teterin wrote:

Hello!

I need multiple threads to be able to operate on the same Map. The HashMap's
documentation at

 http://java.sun.com/javase/6/docs/api/java/util/HashMap.html

advises the following construct:

 Map m = Collections.synchronizedMap(new HashMap(...));

However, the HashTable is, supposedly, inherently thread-safe.

What's better? I saw somewhere, that HashTable is a "legacy" class -- is
that true?

Thanks!

 -mi


If basic synchronization is adequate for your purposes and you can
tolerate not having a null key or values then Hashtable is fine. If you
are going to iterate over the Hashtable and it is possible that you
could modify it in another thread you will need more synchronization.

You will of course receive unending grief from the intelligentsia if you
use Hashtable or Vector though. I just ignore them.

--

Knute Johnson
email s/knute/nospam/

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