What is HashMap and Map?

Map is Interface and Hashmap is class that implements that and its not serialized HashMap is non serialized and Hashtable is serialized.

Interview Candidate
Dec 18th, 2003
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Java

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svsathya

Mar 31st, 2007

An object that maps keys to values. A map cannot contain duplicate keys; each key can map to at most one value
This implementation provides all of the optional map operations, and permits null values and the null key
map implementations, like the TreeMap class, make specific guarantees as to their order; others, like the HashMap class, do not.

Ashish

Jul 23rd, 2014

HashMap works on the principle of hashing. In order to understand the working of HashMap one has to understand hashing.

Below link can be useful to find out the working of HashMap

http://newtechnobuzzz.blogspot.com/2014/07/how-hashmap-works-in-java.html