What setting affects the expansion of bucket storage within the HashMap structure?

In Java, HashMap expands its bucket storage (i.e., increases the number of buckets for storing elements) when a certain fill threshold is reached, which is set by the load factor parameter. By default, the load factor is 0.75, meaning that when 75% of the current buckets are filled, a resize occurs with the number of buckets doubling.

Therefore, the setting that affects the expansion of the bucket storage is the load factor. When creating a HashMap, you can specify this parameter:

HashMap<K, V> map = new HashMap<>(initialCapacity, loadFactor);

Where:

• initialCapacity — the initial number of buckets
• loadFactor — the load factor, after which expansion occurs

If you decrease the load factor, expansion will happen more frequently, but search will be faster due to lower element density in the buckets. If you increase it, expansion will be less frequent, but performance may degrade due to increased collisions.