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hashmap and equals doubts

naved momin
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Joined: Jul 03, 2011
Posts: 688

i have just one question here regarding equals method
please see the output below


if you look at the out put carefully and code you will find that value of this.name changes whenever hashmap put's or get's the value thats the only thing left here i m not getting
can any one explain ?

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Ireneusz Kordal
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Joined: Jun 21, 2008
Posts: 423
naved momin wrote:
if you look at the out put carefully and code you will find that value of this.name changes whenever hashmap put's or get's the value thats the only thing left here i m not getting
can any one explain ?

Hi,

follow this link : http://www.docjar.com/html/api/java/util/Hashtable.java.html
This code is an implementation of HashTable in Java.
Look at these lines, this is a way Hastable.put() is implemented:


Do you see it ?
All your objects have the same hash value.
So HashTable stores them in the same bucket ( tab[ (hash & 0x7FFFFFFF) % tab.length ] ).
Buckets are implemented as simple arrays.
HashTable loops through all elements of this bucked (array) and for each table element calls it's element.equals( key ) method.
naved momin
Ranch Hand

Joined: Jul 03, 2011
Posts: 688

HashTable loops through all elements of this bucked (array) and for each table element calls it's element.equals( key ) method.

thats why "this.name" always changes when i call and "obj.name" remain same ?
 
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