HashMap vs Hashtable: Structure & Differences

Both HashMap and Hashtable are data structures based on hash tables, using arrays combined with linked lists or red-black trees to store key-value pairs. In hash tables, each key-value pair is calculated to a hash value through a hash function, then mapped to a specific position in the hash table based on the hash value, thus enabling fast insertion, retrieval, and deletion operations. The main difference between the two is that Hashtable is thread-safe, while HashMap is not thread-safe.