In today's insightful lesson, we embark on a journey through a pivotal part of Kotlin's collection framework, the HashMap. Building upon our understanding of HashSet from previous lessons, this session introduces you to HashMap, a versatile structure that maintains key-value pairs. This feature makes the HashMap an excellent choice when fast data access via keys is required.
HashMaps in Kotlin leverage the foundation of hashing, enabling average constant time complexity for core operations, such as retrieval and insertion, enhancing their performance. By the end of this lesson, you will gain practical knowledge of creating, manipulating, and understanding the workings of HashMaps, including their implementation and complexity in handling data.
Before we proceed, let's formally define a HashMap. In Kotlin, a HashMap is a collection designed to store key-value pairs, where each key is unique and pairs are grouped by a hash code derived from the key. HashMaps do not assure any particular order of the stored pairs; consequently, the order can change over time.
HashMaps operate on the principle of hashing. A key is transformed into a hash code via a hash function, and this numeric code determines the storage location for the key-value pair. Let's illustrate a straightforward creation of a :
