Creating an Address Book Application with Kotlin MutableMap

Efficient Lookups: Maps offer a fast average time complexity for lookups. This means retrieving a contact&#x27;s phone number by name is efficient, even with a large set of contacts.
Uniqueness: Maps ensure that keys (in this case, contact names) are unique, preventing duplicate entries and simplifying data integrity management.
Readability: The syntax for accessing map entries is clear and concise, making the code easy to read and maintain.
Null Safety: Kotlin’s type system allows us to explicitly handle nullable values, making it easier to work with potentially missing data and reducing runtime errors.

Introduction

Welcome! Today, we will explore creating a simple address book application using Kotlin's collections, specifically mutable maps. This task will help you understand how to manipulate maps in Kotlin, focusing on adding, retrieving, and deleting entries. By the end of this lesson, you'll have a solid grasp of these fundamental operations.

Introducing Methods to Implement

In this task, we will implement three methods to manage our address book:

addContact(name: String, phoneNumber: String): Boolean: Adds a new contact. Returns false if the contact already exists, otherwise adds the contact and returns true. In this task, let's assume phone numbers do not change, so it's not allowed to overwrite the existing contact's number.
getContact(name: String): String?: Retrieves the phone number for a given name. Returns null if the contact does not exist.
deleteContact(name: String): Boolean: Deletes a contact with the given name. Returns true if the contact exists and is deleted; otherwise.

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