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HashMap VS HashSet Java: In this article, we will discuss the difference between HashMap and HashSet Java classes in detail i.e.; HashMap VS HashSet Java.
Read Also: HashMap VS LinkedHashMap vs TreeMap In Java
HashMap VS HashSet Java
| HashMap | HashSet |
| It implements Map interface | It implements Set interface |
| Used to store key-value pairs using put method example: hm.put(key, value); | Used to store only unique objects using add method example: hs.add(object); |
| It doesn’t allow duplicate keys but values can be duplicated | HashSet doesn’t allow duplicate objects |
| It allows a maximum of one null key but any number of NULL values allowed | HashSet allows a maximum of one null object to be added |
| It internally uses an array of Entry<K, V> objects | HashSet internally uses HashMap to store unique objects |
| Performance-wise, HashMap is faster than HashSet | Performance-wise, HashSet is slower than HashMap |
When to use HashMap?
- It stores key-value pairs which use a hashing technique to store key-value pairs where methods are NOT synchronized
- So, the search operation is faster with multiple threads access
- So, if a business requirement is to store key-value pairs for faster search operation or number of search operation on the basis of keys; without concerning concurrent access to the map
- Then, HashMap is the very apt choice
Read Also: ArrayList VS LinkedList In Java
When to use HashSet?
- HashSet stores unique elements using the hashing technique
- So, the search operation is faster
- So, if the business requirement is to store unique elements for faster search operation or more number of search operation without concerning insertion order
- Then, HashSet is the very apt choice
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