HashSet Vs LinkedHashSet
The HashSet is a class of Java collection framework used to create a collection that uses a hashtable for storing the object. In contrast, the LinkedHashSet class is similar to the HashSet. Moreover, it maintains the insertion order.
The HashSet inherits the properties of the AbstractSet class and implements the Set interface. The LinkedHashSet inherits the HashSet class and implements the Set interface.
The HashSet is a class that implements the Set interface. It is used to store the objects in a hashtable; a hashtable is a data structure, which stores data in an ArrayList. It provides quick access to the data using the array index. We can insert, update, and remove the elements easily using a HashSet.
Below are some features of the HashSet class:
A HashSet class can be declared as follows:
Consider the below example to understand the behavior of HashSet:
Apple Cat Elephant Dog Banana
From the above example, we can see the elements are stored in an unordered collection.
LinkedHashSet class is quite similar to the HashSet class; it is an ordered version of HashSet. Moreover, it allows us to maintain the insertion order of the elements. It inherits the HashSet class and implements the Set interface. It also uses a hashtable to store the elements. It allows us to easily insert, update, remove, and maintain the elements.
Below are some features of the LinkedHashSet:
A LinkedHashSet class can be declared as follows:
Consider the below example to understand the behavior of LinkedHashSet:
A B C D E
From the above example, we can see the elements are iterated in insertion order.
Difference between HashSet and LinkedHashSet
Below are some key differences between HashSet and LinkedHashSet:
Consider the below tabular differences between HashSet and LinkedHashSet:
When to use HashSet and LinkedHashSet
If we are required to maintain the insertion order, then the LinkedHashSet will be useful. But, when maintaining the insertion order of the elements is not our priority, the HashSet will be useful and provide improved performance.
As we have discussed both HashSet and LinkedHashSet classes of the Java collection framework, Adding a final note to this discussion, we would like to say that both data structures are very useful and use a similar implementation technique (Hashing). But, if you have a minor project where the insertion order is not necessary, we will recommend using the HashSet as it provides improved performance than LinkedHashSet. If you want to predict the insertion order, then the use of LinkedHashSet is recommended as it uses a doubly linked list to maintain the order of the element and provides an easy search process.