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Object as a HashMap key

 
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I have read that Object is not suitable as a HashMap key.
What is wrong with mapping an object reference to a value?


A map m is said to contain a mapping for a key k if and only if m.containsKey(k) would return true.


[ October 28, 2003: Message edited by: Marlene Miller ]
 
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I have read that Object is not suitable as a HashMap key.
What is wrong with mapping an object reference to a value?


I think it is more appropriate to use a subclass because the hashcode() implementation can be more specialized and therefore more efficient.
 
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don't forget the golden rule -- if you override hashcode, you have to override equals() and vice versa -- otherwise all the hashtable stuff goes awry.
 
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