Explain internal working of a hashset

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Accepted Answer

HashSet is a collection that uses hashing to store elements. It does not allow duplicates.

HashSet internally uses a HashMap to store elements.
The elements are stored as keys in the HashMap with a dummy value.
When an element is added, its hashcode is calculated and used to find the bucket in the HashMap.
If the bucket is empty, the element is added as a key with a dummy value.
If the bucket is not empty, the element is compared with the existing elements in the bucket using equals() method.
If the element already exists, it is not added.
If the element does not exist, it is added as a key with a dummy value.
When an element is removed, its hashcode is used to find the bucket and then the element is removed from the bucket.
The size of the HashSet is the number of keys in the HashMap.

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