What is the internal working of HashMap?

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HashMap is a data structure that stores key-value pairs using hashing for efficient retrieval and storage.

1. HashMap uses an array of buckets to store entries, where each bucket can hold multiple entries in case of collisions.
2. It calculates the hash code of the key to determine the index in the array where the value will be stored.
3. When two keys hash to the same index, a linked list or tree structure is used to store multiple entries (Java 8+ uses trees for large buckets).
4. The load factor (default 0.75) determines when to resize the HashMap to maintain performance.
5. Example: Inserting a key-value pair ("A", 1) involves computing the hash of "A" and placing it in the corresponding bucket.

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