java question.

[Rajesh Inakota]

When to use ConcurrentHashMap?

what is the difference between HashMap, HashTable and CorrentHashMap ?

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Regards,
Rajesh.I

[SURI]

HashMap -- Offers non-synchronized methods.  -- Better response 

HashTable -- Offers synchronized methods with map level locks.  -- Slow response

ConcurrentHashMap -- Similar to HashTable with bucket level locking.. Performance of this is approach is some where in the middle of HashTable and HashMap.

-- SURI

[Shyam Prakash Velupula]

Suresh,

Does HashMap handle queries in async fashion?

- Shyam

--
You are limited only by your imagination

[SURI]

Shyam, I meant to say HashMap is not thread safe but HashTable is
thread safe.

But there is a way to make the HashMap thread safe :
Hashmap map = Collections.synchronizedMap(new HashMap(..))

There is another difference HashMap and HashTable is allowing null
values. HashTable doesn't allow null values as a key or a value.
Correct me if I am wrong here.

-- SURI

On Jul 13, 8:04 am, Shyam Prakash Velupula <velup...@gmail.com> wrote:
> Suresh,
>
> Does HashMap handle queries in async fashion?
>
> - Shyam
>

[Shyam Prakash Velupula]

Suresh,

Thanks for clarifying. I misunderstood the word "synchronized".
Actually, I have very basic understanding of Java.


- Shyam