Apr 6, 2023 · HashSet internally uses HashMap to add elements. In HashSet, the argument passed in add (Object) method serves as key K. Java internally associates dummy value for each value passed in add (Object) method.

Mar 21, 2024 · Difference between HashMap vs HashSet is:-HashMap contains key value pairs and each value can be accessed by key where as HashSet needs to be iterated everytime as there is no get method.

Mar 12, 2025 · HashSet in Java implements the Set interface of Collections Framework. It is used to store the unique elements and it doesn’t maintain any specific order of elements. Can store the Null values. Uses HashMap (implementation of hash table data structure) internally. Also implements Serializable and Cloneable interfaces. HashSet is not thread-safe.

HashMap and Hashtable stores values in key-value pair. HashSet contains unique elements and HashMap, HashTable contains unique keys. Having these similarities they have some differences also. HashSet inherits AbstractSet class and implements Set interface. Set objects are always unique and no duplicate objects are allowed.

Apr 5, 2015 · HashSet is backed by a HashMap, so in a HashSet when we call .add(element), we are calling the hashCode() method on the element and internally doing a put(k,v) to the internal HashMap, where the key is the hashCode and the value is the actual object.

HashSet implements the Set interface while HashMap implements the Map interface. The Set interface extends the Collection interface, but the Map interface is an entirely separate one. HashSet stores single objects, while HashMap stores key-value pairs (entries).

HashSet uses internally HashMap with dummy object named PRESENT as value and KEY of this hashmap will be your object. hash(simpleObject1) and hash(simplObject2) will return the same int. So?

Mar 25, 2025 · In Java, HashMap vs HashSet in Java highlights two important collection classes with distinct purposes. HashMap stores key-value pairs, making it useful for fast lookups and data management. In contrast, HashSet stores only unique elements, ensuring no duplicates.

Mar 23, 2025 · Whenever you create a HashSet, Java creates a hidden HashMap and inserts the element as a key, while the value is a dummy constant. This means when you do: HashSet<String> set = new HashSet ...

Jan 22, 2023 · HashSet is the best choice if we perform search operations. The HashMap class was introduced in the Java 1.2 version and is available in the java.util package. HashMap is a child class of the AbstractMap class, and it implements the Map interface as well as the Cloneable and Serializable interfaces.