How does the number of buckets in a HashMap grow when adding elements?

In Java, the HashMap's number of buckets increases when elements are added and the number exceeds the threshold, which is equal to capacity * load factor (default load factor = 0.75). When this threshold is reached, a resize operation occurs, during which the size of the bucket array doubles, and all existing elements are redistributed across the new buckets considering the new size.

For example: if the initial capacity is 16, then adding 12 elements (16 * 0.75) will trigger an expansion to 32 buckets.

This helps maintain efficient access and insertion times by reducing the number of collisions.