In what situations is it preferable to use the HashMap data structure for storing key-value pairs?

HashMap is preferable when you need to efficiently store and quickly access data by key. Main situations:

• Frequent search, insertion, and deletion operations by key with amortized complexity O(1).
• When the order of elements does not matter.
• Keys are unique and well-hashed.

For example, if you need to store application settings where the key is the setting name and the value is its parameter, HashMap allows quick retrieval of the required value.

Example in Kotlin:

val map = HashMap<String, Int>()
map["apple"] = 3
map["banana"] = 5
println(map["apple"]) // 3