What is the main component used inside the HashMap data structure for storing and quickly accessing objects?

The main component inside the HashMap data structure in Java is the array of buckets, where each bucket is a linked list or a tree (starting from Java 8) of elements with the same hash code. A hash function is used for quick access to objects, which calculates the index of the bucket in the array. If there are multiple elements in a bucket (collision), they are stored as a linked list or a balanced tree (TreeNode), allowing efficient search for the desired element.