How is the Bucket structure implemented inside HashMap and how does it affect the hash table's operation?

In HashMap, the Bucket structure is a container for storing elements that have the same hash code (after applying the hash function and calculating the index). In earlier Java versions, Bucket was implemented as a linked list, where all collision elements were stored sequentially.

In newer versions (starting from Java 8), when a certain list length threshold is reached, the Bucket is transformed into a balanced tree (such as a red-black tree), which improves search performance from O(n) to O(log n) in case of many collisions.

Thus, Bucket affects hash table operation as follows:

• It provides storage for multiple elements with the same index.
• It allows efficient collision resolution.
• It improves get/put operation performance under high collision scenarios by transitioning from list to tree.