What is the difference between HashSet and HashMap In Java ?

Here we list all the differences between HashSet and HashMap In Java.

Know Also : Set Interface / Map Interface / HashSet / HashMap

HashSet	HashMap
It implements the Set Interface.	It implements the Map Interface.
HashSet only store values.	HashMap store data in form of key-value pair.
HashSet does not allow duplicate values.	In HashMap keys cannot be duplicate while values can be duplicate.
HashSet allows one null value.	HashMap allows one null key and multiple null values.
It internally uses HashMap to add elements.	It internally uses hashing to add elements.
add() method is used to add element in HashSet.	put(k,v) method is used to add key-value pair in HashMap.
HashSet uses equal() method for camparison.	HashMap uses hashCode() and equal() methods for camparison.
It can be synchronized by using : HashSet<String>  set = new HashSet<>(); Collections.synchronizedSet(set);	It can be synchronized by using : HashMap<String, String> map = new HashMap<>(); Collections.synchronizedMap(map);

Some similarities between HashSet and HashMap are as follows:

HashSet	HashMap
It is not synchronized.	It is not synchronized.
It is not Thread-safe.	It is not Thread-safe.
It is a fail-fast iterator.	It is a fail-fast iterator.
No guarantee about elements order.	No guarantee about elements order.

      

Blog Author - Pushkar Khosla,
Software Developer by Profession with 3.0 Yrs of Experience , through this blog i'am sharing my industrial Java Knowledge to entire world. For any question or query any one can comment below or mail me at pushkar.itsitm52@gmail.com.

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