HashMap Class in Java
What is HashMap in Java?
Java's HashMap class is a Hash Table implementation of Map interface. It stores data in key-value pairs.
When to use HashMap in Java?
Unlike an ArrayList, HashMap implementations don't use indices to sort values. Therefore to access each entry, one must know the key of the entry/object.
So if you have several key-value pairs or data that can be identified using keys, then Java's HashMap class is for you.
More about HashMap
The keys used to store data must be unique, which means multiple entries with same key is not possible in HashMap. Also, there's no order to those entries.
The HashMap class extends AbstractMap class and implements the Map interface in Java.
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