mutableListOf

mutableListOf is a Kotlin standard library function that creates a new mutable list, which is a collection that allows elements to be added, removed, and modified after creation. This function returns an instance of MutableList, a generic interface that extends both List and MutableCollection interfaces.

The mutableListOf function can be called with or without initial elements. When called without parameters, it creates an empty mutable list. When provided with elements as arguments, it initializes the list with those values. For example, mutableListOf() creates an empty list, while mutableListOf(1, 2, 3) creates a list containing three integers.

The returned MutableList supports standard mutator operations including add(), remove(), clear(), and set() methods. Elements can be appended to the end of the list using add(), specific elements can be removed by value or index, and existing elements can be replaced using indexing operations. The list automatically resizes as elements are added or removed.

Unlike listOf() which creates immutable lists, mutableListOf provides flexibility for dynamic data manipulation. However, this comes with considerations regarding thread safety and performance implications of frequent modifications. The underlying implementation typically uses arrays that may need resizing during growth operations.

The function is generic, allowing specification of the element type through type parameters or relying on type inference from the provided initial values. Type safety is maintained at compile time, preventing incompatible types from being added to typed lists.

mutableListOf is commonly used in scenarios requiring dynamic collection management, such as building lists incrementally, implementing algorithms that modify collections, or when interfacing with APIs requiring mutable collections. It provides a balance between functionality and performance for general-purpose list operations in Kotlin applications.