Hashset Vs Hashmap | Difference | Comparison

HashSet is a collection that only stores unique elements and doesn't allow delicate elements. It doesn't provide any methods to retrieve elements. While hashmap is a collection that stores elements in key-value pairs and allow duplicate values. It provides various methods to retrieve elements. Let us discuss the difference of Hashset Vs Hashmap with the help of the comparison given below.

What is HashSet?

HashSet is an implementation set interface which does not allow duplicate values. The main thing is, an object that is stored in HashSet must override equals() to check for equality and hashcode() methods for no duplicate value are stored in our set.

Learn more about Tree set Vs Treemap

What is a Hashmap?

An implementation of the map interface that maps a key to a value is called a hashmap. On a map, duplicate keys are not permitted. Basically, there are two implementation classes for the map interface: hashmap and treemap. The primary distinction between the two is that treemap preserves object order whereas hashmap does not. Hashmap accepts null keys and null values. HashSet and hashmap aren't synced with one another.

HashSet Vs Hashmap | Difference between HashSet and hashmap:

• Java Hashmap is a hash table-based implementation of the MAP interface. Harshest is a set. It creates a collection that uses a hash table for storage. 
• Hashmap implements MAP, cloneable, and serializable interface es. Harshest implement set, cloneable serializable, iterable and collection interfaces. 
• In hashmap, we store a key-value pair. It keeps the mapping between the key and value.. In HashSet, we store objects.
• Hashmap can contain a single null key and multiple null values. While HashSet can contain a single null value.
• The put() function is used by hashmap to add entries. HashSet uses the add() method element in the HashSet.
• Hashmap does not allow duplicate keys, but duplicate values are allowed. While HashSet does not allow duplicate values.
• Since each value has a distinct key, hashmap is quicker than HashSet. HashSet is slower than hashmap the member object is used for calculating the hashcode value, which can be the same for two objects. 
• Hashmap is only one object created during the add operation. There are two objects created during the put operation, one for key and one for value. 
• Hashmap internally uses hashing to store objects. A hashmap object is used by HashSet internally to store things.
• Always hashmap prefers when we do not maintain the uniqueness. While HashSet is used when we need to maintain the uniqueness of data.

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