Difference Between HashMap and HashSet

Both of these are classes used in the Java collection framework, and they are the most popular ones among all. We can use them for data structuring, but there is a significant difference between HashMap and HashSet. In this article, we will discuss the same in detail.

What is HashMap?

It is a type of implementation of the Map Interface that maps its keys to the values. A map does not allow any duplicate keys in it. Here, a Map Interface basically has two types of implementation classes- the TreeMsp and the HashMap. The primary difference here is that TreeMap maintains the intended order of the available objects while HashMap does not. HashMap basically allows null keys as well as null values.

Both the HashMap and HashSet do not stay synchronized.

What is HashSet?

It is a type of implementation of the Set Interface that allows no duplication of the value. The objects that get stored in the HashSet need to override the equals() to check the equality. It also uses the hashCode() method because it doesn’t store any duplicate values in the set.

Difference Between HashMap and HashSet

Here is a list of the differences between HashMap and HashSet.

Parameters HashMap HashSet
Implementation It implements the Map Interface. It implements the Set Interface.
Total Number of Storing Objects It requires two of the objects when adding any element to the HashMap object- namely V value and K key. A set of HashSet requires only one object when adding- that is, Object O.
Duplicate Values It does not allow any duplicate values. It stores the value pairs and keys, and it does not allow any duplicate keys. Here, if a key turns out to be old, then it replaces this key with a new value.
Dummy Value The HashMap does not come with any concept of Dummy value. It initially makes use of HashMap for adding elements. The argument that passes in the add(object) method in HashSet serves as the key K. Java associates the dummy value for individual values passing in the add(object) method internally.
Speed It is comparatively faster than HashSet. It is comparatively slower than HashMap.
Adding or Storing Mechanism It stores or adds various objects by making use of hashing internally. It internally makes use of the HashMap objects for adding or storing the objects.
Insertion It stores data using the put() method. It stores data using the add() method.

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